Fundamental Physical Constants

Fundamental Physical Constants

Revi: 2018-07-15 03:55:00 +08 @ China-Guangdong-Zhanjiang +08 Auth: BSS9395 Reso: CODATA_2014

Conversion of Units

$12 u = \dfrac{12}{N_\mathrm{A}} g$

$F = N_\mathrm{A} \cdot e$

$R = k \cdot N_\mathrm{A}$

$12 u = \dfrac{12}{N_\mathrm{A}} g$
$F = N_\mathrm{A} \cdot e$
$R = k \cdot N_\mathrm{A}$

Estimate

Symbol Numerical Value Unit

$\dfrac{e^2}{4 \pi \epsilon_0}$ $\approx 1.44$ $\mathrm{fm \cdot M eV}$

$r_\mathrm{e} = \dfrac{e^2}{4 \pi \epsilon_0 m_\mathrm{e} c^2}$ $\approx 2.818$ $\mathrm{fm}$

Symbol	Numerical Value	Unit
$\dfrac{e^2}{4 \pi \epsilon_0}$	$\approx 1.44$	$\mathrm{fm \cdot M eV}$
$r_\mathrm{e} = \dfrac{e^2}{4 \pi \epsilon_0 m_\mathrm{e} c^2}$	$\approx 2.818$	$\mathrm{fm}$

Universal

Symbol Numerical Value Unit Relative Standard Uncertainty Quantity

$c, c_0$ $299792458$ $\mathrm{m \cdot s^{-1}}$ Exact Speed of light in vacuum

$\mu_0$ $4 \pi \times 10^{- 7}$ $= 12.566370614 \dots \times 10^{- 7}$ $\mathrm{N \cdot A^{- 2}}$ Exact Magnetic constant

$\epsilon_0$ $8.854187817 \ldots \times 10^{- 12}$ $\mathrm{F \cdot m^{- 1}}$ Exact Electric constant $\dfrac{1}{\mu_0 c^2}$

$Z_0$ $376.730313461 \ldots$ $\mathrm{\Omega}$ Exact Characteristic impedance of vacuum $μ_0 c$

$G$ $6.67408(31) \times 10^{- 11}$ $\mathrm{m^3 \cdot kg^{- 1} \cdot s^{- 2}}$ $4.7 \times 10^{- 5}$ Newtonian constant of gravitation

$\dfrac{G}{\hbar c}$ $6.70861(31) \times 10^{- 39}$ $\mathrm{\left(\dfrac{G eV}{c^2}\right)^{- 2}}$ $4.7 \times 10^{- 5}$ Newtonian constant of gravitation

$h$ $6.626070040(81) \times 10^{- 34}$ $\mathrm{J \cdot s}$ $1.2 \times 10^{- 8}$ Planck constant

$h$ $4.135667662(25) \times 10^{- 15}$ $\mathrm{eV \cdot s}$ $6.1 \times 10^{- 9}$ Planck constant

$\hbar$ $1.054571800(13) \times 10^{- 34}$ $\mathrm{J \cdot s}$ $1.2 \times 10^{- 8}$ Planck constant $\dfrac{h}{2 \pi}$

$\hbar$ $6.582119514(40) \times 10^{- 16}$ $\mathrm{eV \cdot s}$ $6.1 \times 10^{- 9}$ Planck constant $\dfrac{h}{2 \pi}$

$\hbar c$ $197.3269788(12)$ $\mathrm{M eV \cdot fm}$ $6.1 \times 10^{- 9}$ Planck constant

$m_\mathrm{P}$ $2.176470(51) \times 10^{- 8}$ $\mathrm{kg}$ $2.3 \times 10^{- 5}$ Planck mass $\left(\dfrac{\hbar c}{G}\right)^\frac{1}{2}$

$m_\mathrm{P} c^2$ $1.220910(29) \times 10^{19}$ $\mathrm{G eV}$ $2.3 \times 10^{- 5}$ Planck mass $\left(\dfrac{\hbar c}{G}\right)^\frac{1}{2}$ energy equivalent

$T_\mathrm{P}$ $1.416808(33) \times 10^{32}$ $\mathrm{K}$ $2.3 \times 10^{- 5}$ Planck temperature $\dfrac{\left(\dfrac{\hbar c^5}{G}\right)^\frac{1}{2}}{k}$

$l_\mathrm{P}$ $1.616229(38) \times 10^{- 35}$ $\mathrm{m}$ $2.3 \times 10^{- 5}$ Planck length $\dfrac{\hbar}{m_\mathrm{P} c} = \left(\dfrac{\hbar G}{c^3}\right)^\frac{1}{2}$

$t_\mathrm{P}$ $5.39116(13) \times 10^{- 44}$ $\mathrm{s}$ $2.3 \times 10^{- 5}$ Planck time $\dfrac{l_\mathrm{P}}{c} = \left(\dfrac{\hbar G}{c^5}\right)^\frac{1}{2}$

Symbol	Numerical Value	Unit	Relative Standard Uncertainty	`Quantity`
$c, c_0$	$299792458$	$\mathrm{m \cdot s^{-1}}$	Exact	Speed of light in vacuum
$\mu_0$	$4 \pi \times 10^{- 7}$ $= 12.566370614 \dots \times 10^{- 7}$	$\mathrm{N \cdot A^{- 2}}$	Exact	Magnetic constant
$\epsilon_0$	$8.854187817 \ldots \times 10^{- 12}$	$\mathrm{F \cdot m^{- 1}}$	Exact	Electric constant $\dfrac{1}{\mu_0 c^2}$
$Z_0$	$376.730313461 \ldots$	$\mathrm{\Omega}$	Exact	Characteristic impedance of vacuum $μ_0 c$
$G$	$6.67408(31) \times 10^{- 11}$	$\mathrm{m^3 \cdot kg^{- 1} \cdot s^{- 2}}$	$4.7 \times 10^{- 5}$	Newtonian constant of gravitation
$\dfrac{G}{\hbar c}$	$6.70861(31) \times 10^{- 39}$	$\mathrm{\left(\dfrac{G eV}{c^2}\right)^{- 2}}$	$4.7 \times 10^{- 5}$	Newtonian constant of gravitation
$h$	$6.626070040(81) \times 10^{- 34}$	$\mathrm{J \cdot s}$	$1.2 \times 10^{- 8}$	Planck constant
$h$	$4.135667662(25) \times 10^{- 15}$	$\mathrm{eV \cdot s}$	$6.1 \times 10^{- 9}$	Planck constant
$\hbar$	$1.054571800(13) \times 10^{- 34}$	$\mathrm{J \cdot s}$	$1.2 \times 10^{- 8}$	Planck constant $\dfrac{h}{2 \pi}$
$\hbar$	$6.582119514(40) \times 10^{- 16}$	$\mathrm{eV \cdot s}$	$6.1 \times 10^{- 9}$	Planck constant $\dfrac{h}{2 \pi}$
$\hbar c$	$197.3269788(12)$	$\mathrm{M eV \cdot fm}$	$6.1 \times 10^{- 9}$	Planck constant
$m_\mathrm{P}$	$2.176470(51) \times 10^{- 8}$	$\mathrm{kg}$	$2.3 \times 10^{- 5}$	Planck mass $\left(\dfrac{\hbar c}{G}\right)^\frac{1}{2}$
$m_\mathrm{P} c^2$	$1.220910(29) \times 10^{19}$	$\mathrm{G eV}$	$2.3 \times 10^{- 5}$	Planck mass $\left(\dfrac{\hbar c}{G}\right)^\frac{1}{2}$ energy equivalent
$T_\mathrm{P}$	$1.416808(33) \times 10^{32}$	$\mathrm{K}$	$2.3 \times 10^{- 5}$	Planck temperature $\dfrac{\left(\dfrac{\hbar c^5}{G}\right)^\frac{1}{2}}{k}$
$l_\mathrm{P}$	$1.616229(38) \times 10^{- 35}$	$\mathrm{m}$	$2.3 \times 10^{- 5}$	Planck length $\dfrac{\hbar}{m_\mathrm{P} c} = \left(\dfrac{\hbar G}{c^3}\right)^\frac{1}{2}$
$t_\mathrm{P}$	$5.39116(13) \times 10^{- 44}$	$\mathrm{s}$	$2.3 \times 10^{- 5}$	Planck time $\dfrac{l_\mathrm{P}}{c} = \left(\dfrac{\hbar G}{c^5}\right)^\frac{1}{2}$

Non-SI Units Accepted for Use with the SI

Symbol Numerical Value Unit Relative Standard Uncertainty Quantity

$\mathrm{eV}$ $1.6021766208(98) \times 10^{- 19}$ $\mathrm{J}$ $6.1 \times 10^{- 9}$ Electron volt $\dfrac{e}{\mathrm{C}} \mathrm{J}$

$\mathrm{u}$ $1.660539040(20) \times 10^{- 27}$ $\mathrm{kg}$ $1.2 \times 10^{- 8}$ (Unified) atomic mass unit $\dfrac{1}{12} m (\ce{^{12} C})$

$\mathrm{Jy}$ $10^{- 26}$ $\mathrm{W \cdot m^{- 2} \cdot Hz^{- 1}}$

$\mathrm{Jy}$ $10^{- 23}$ $\mathrm{erg \cdot s^{- 1} \cdot cm^{- 2} \cdot Hz^{- 1}}$

Symbol	Numerical Value	Unit	Relative Standard Uncertainty	`Quantity`
$\mathrm{eV}$	$1.6021766208(98) \times 10^{- 19}$	$\mathrm{J}$	$6.1 \times 10^{- 9}$	Electron volt $\dfrac{e}{\mathrm{C}} \mathrm{J}$
$\mathrm{u}$	$1.660539040(20) \times 10^{- 27}$	$\mathrm{kg}$	$1.2 \times 10^{- 8}$	(Unified) atomic mass unit $\dfrac{1}{12} m (\ce{^{12} C})$
$\mathrm{Jy}$	$10^{- 26}$	$\mathrm{W \cdot m^{- 2} \cdot Hz^{- 1}}$
$\mathrm{Jy}$	$10^{- 23}$	$\mathrm{erg \cdot s^{- 1} \cdot cm^{- 2} \cdot Hz^{- 1}}$

Electromagnetic

Symbol Numerical Value Unit Relative Standard Uncertainty Quantity

$e$ $1.6021766208(98) \times 10^{- 19}$ $\mathrm{C}$ $6.1 \times 10^{- 9}$ Elementary charge

$\dfrac{e}{h}$ $2.417989262(15) \times 10^{14}$ $\mathrm{A \cdot J^{- 1}}$ $6.1 \times 10^{- 9}$ Elementary charge

$\Phi_0$ $2.067833831(13) \times 10^{- 15}$ $\mathrm{Wb}$ $6.1 \times 10^{- 9}$ Magnetic flux quantum $\dfrac{h}{2 e}$

$G_0$ $7.7480917310(18) \times 10^{- 5}$ $\mathrm{S}$ $2.3 \times 10^{- 10}$ Conductance quantum $\dfrac{2 e^2}{h}$

$G_0^{- 1}$ $12906.4037278(29)$ $\mathrm{\Omega}$ $2.3 \times 10^{- 10}$ Conductance quantum $\dfrac{2 e^2}{h}$, inverse of conductance quantum

$K_\mathrm{J}$ $483597.8525(30) \times 10^9$ $\mathrm{Hz \cdot V^{- 1}}$ $6.1 \times 10^{- 9}$ Josephson constant $\dfrac{2 e}{h}$

$R_\mathrm{K}$ $25812.8074555(59)$ $\mathrm{\Omega}$ $2.3 \times 10^{- 10}$ von Klitzing constant $\dfrac{h}{e^2} = \dfrac{\mu_0 c}{2 \alpha}$

$\mu_\mathrm{B}$ $927.4009994(57) \times 10^{- 26}$ $\mathrm{J \cdot T^{- 1}}$ $6.2 \times 10^{- 9}$ Bohr magneton $\dfrac{e \hbar}{2 m_e}$

$\mu_\mathrm{B}$ $5.7883818012(26) \times 10^{- 5}$ $\mathrm{eV \cdot T^{- 1}}$ $4.5 \times 10^{- 10}$ Bohr magneton $\dfrac{e \hbar}{2 m_e}$

$\dfrac{\mu_\mathrm{B}}{h}$ $13.996245042(86) \times 10^9$ $\mathrm{Hz \cdot T^{- 1}}$ $6.2 \times 10^{- 9}$ Bohr magneton $\dfrac{e \hbar}{2 m_e}$

$\dfrac{\mu_\mathrm{B}}{h c}$ $46.68644814(29)$ $\mathrm{m^{- 1} \cdot T^{- 1}}$ $6.2 \times 10^{- 9}$ Bohr magneton $\dfrac{e \hbar}{2 m_e}$

$\dfrac{\mu_\mathrm{B}}{k}$ $0.67171405(39)$ $\mathrm{K \cdot T^{- 1}}$ $5.7 \times 10^{- 7}$ Bohr magneton $\dfrac{e \hbar}{2 m_e}$

$\mu_\mathrm{N}$ $5.050783699(31) \times 10^{- 27}$ $\mathrm{J \cdot T^{- 1}}$ $6.2 \times 10^{- 9}$ Nuclear magneton $\dfrac{e \hbar}{2 m_\mathrm{p}}$

$\mu_\mathrm{N}$ $3.1524512550(15) \times 10^{- 8}$ $\mathrm{eV \cdot T^{- 1}}$ $4.6 \times 10^{- 10}$ Nuclear magneton $\dfrac{e \hbar}{2 m_\mathrm{p}}$

$\dfrac{\mu_\mathrm{N}}{h}$ $7.622593285(47)$ $\mathrm{M Hz \cdot T^{- 1}}$ $6.2 \times 10^{- 9}$ Nuclear magneton $\dfrac{e \hbar}{2 m_\mathrm{p}}$

$\dfrac{\mu_\mathrm{N}}{h c}$ $2.542623432(16) \times 10^{- 2}$ $\mathrm{m^{- 1} \cdot T^{- 1}}$ $6.2 \times10^{- 9}$ Nuclear magneton $\dfrac{e \hbar}{2 m_\mathrm{p}}$

$\dfrac{\mu_\mathrm{N}}{k}$ $3.6582690(21) \times 10^{- 4}$ $\mathrm{K \cdot T^{- 1}}$ $5.7 \times 10^{- 7}$ Nuclear magneton $\dfrac{e \hbar}{2 m_\mathrm{p}}$

Symbol	Numerical Value	Unit	Relative Standard Uncertainty	`Quantity`
$e$	$1.6021766208(98) \times 10^{- 19}$	$\mathrm{C}$	$6.1 \times 10^{- 9}$	Elementary charge
$\dfrac{e}{h}$	$2.417989262(15) \times 10^{14}$	$\mathrm{A \cdot J^{- 1}}$	$6.1 \times 10^{- 9}$	Elementary charge
$\Phi_0$	$2.067833831(13) \times 10^{- 15}$	$\mathrm{Wb}$	$6.1 \times 10^{- 9}$	Magnetic flux quantum $\dfrac{h}{2 e}$
$G_0$	$7.7480917310(18) \times 10^{- 5}$	$\mathrm{S}$	$2.3 \times 10^{- 10}$	Conductance quantum $\dfrac{2 e^2}{h}$
$G_0^{- 1}$	$12906.4037278(29)$	$\mathrm{\Omega}$	$2.3 \times 10^{- 10}$	Conductance quantum $\dfrac{2 e^2}{h}$, inverse of conductance quantum
$K_\mathrm{J}$	$483597.8525(30) \times 10^9$	$\mathrm{Hz \cdot V^{- 1}}$	$6.1 \times 10^{- 9}$	Josephson constant $\dfrac{2 e}{h}$
$R_\mathrm{K}$	$25812.8074555(59)$	$\mathrm{\Omega}$	$2.3 \times 10^{- 10}$	von Klitzing constant $\dfrac{h}{e^2} = \dfrac{\mu_0 c}{2 \alpha}$
$\mu_\mathrm{B}$	$927.4009994(57) \times 10^{- 26}$	$\mathrm{J \cdot T^{- 1}}$	$6.2 \times 10^{- 9}$	Bohr magneton $\dfrac{e \hbar}{2 m_e}$
$\mu_\mathrm{B}$	$5.7883818012(26) \times 10^{- 5}$	$\mathrm{eV \cdot T^{- 1}}$	$4.5 \times 10^{- 10}$	Bohr magneton $\dfrac{e \hbar}{2 m_e}$
$\dfrac{\mu_\mathrm{B}}{h}$	$13.996245042(86) \times 10^9$	$\mathrm{Hz \cdot T^{- 1}}$	$6.2 \times 10^{- 9}$	Bohr magneton $\dfrac{e \hbar}{2 m_e}$
$\dfrac{\mu_\mathrm{B}}{h c}$	$46.68644814(29)$	$\mathrm{m^{- 1} \cdot T^{- 1}}$	$6.2 \times 10^{- 9}$	Bohr magneton $\dfrac{e \hbar}{2 m_e}$
$\dfrac{\mu_\mathrm{B}}{k}$	$0.67171405(39)$	$\mathrm{K \cdot T^{- 1}}$	$5.7 \times 10^{- 7}$	Bohr magneton $\dfrac{e \hbar}{2 m_e}$
$\mu_\mathrm{N}$	$5.050783699(31) \times 10^{- 27}$	$\mathrm{J \cdot T^{- 1}}$	$6.2 \times 10^{- 9}$	Nuclear magneton $\dfrac{e \hbar}{2 m_\mathrm{p}}$
$\mu_\mathrm{N}$	$3.1524512550(15) \times 10^{- 8}$	$\mathrm{eV \cdot T^{- 1}}$	$4.6 \times 10^{- 10}$	Nuclear magneton $\dfrac{e \hbar}{2 m_\mathrm{p}}$
$\dfrac{\mu_\mathrm{N}}{h}$	$7.622593285(47)$	$\mathrm{M Hz \cdot T^{- 1}}$	$6.2 \times 10^{- 9}$	Nuclear magneton $\dfrac{e \hbar}{2 m_\mathrm{p}}$
$\dfrac{\mu_\mathrm{N}}{h c}$	$2.542623432(16) \times 10^{- 2}$	$\mathrm{m^{- 1} \cdot T^{- 1}}$	$6.2 \times10^{- 9}$	Nuclear magneton $\dfrac{e \hbar}{2 m_\mathrm{p}}$
$\dfrac{\mu_\mathrm{N}}{k}$	$3.6582690(21) \times 10^{- 4}$	$\mathrm{K \cdot T^{- 1}}$	$5.7 \times 10^{- 7}$	Nuclear magneton $\dfrac{e \hbar}{2 m_\mathrm{p}}$

Atomic and Nuclear

General

Symbol Numerical Value Unit Relative Standard Uncertainty Quantity

$\alpha$ $7.2973525664(17) \times 10^{- 3}$ $2.3 \times 10^{- 10}$ Fine-structure constant $\dfrac{e^2}{4 \pi \epsilon_0 \hbar c}$

$\dfrac{1}{\alpha}$ $137.035999139(31)$ $2.3 \times 10^{- 10}$ Fine-structure constant $\dfrac{e^2}{4 \pi \epsilon_0 \hbar c}$, inverse fine-structure constant

$R_\infty$ $10973731.568508(65)$ $\mathrm{m^{- 1}}$ $5.9 \times 10^{- 12}$ Rydberg constant $\dfrac{\alpha^2 m_e c}{2 h}$

$R_\infty c$ $3.289841960355(19) \times 10^{15}$ $\mathrm{Hz}$ $5.9 \times 10^{- 12}$ Rydberg constant $\dfrac{\alpha^2 m_e c}{2 h}$

$R_\infty h c$ $2.179872325(27) \times 10^{- 18}$ $\mathrm{J}$ $1.2 \times 10^{- 8}$ Rydberg constant $\dfrac{\alpha^2 m_e c}{2 h}$

$R_\infty h c$ $13.605693009(84)$ $\mathrm{eV}$ $6.1 \times 10^{- 9}$ Rydberg constant $\dfrac{\alpha^2 m_e c}{2 h}$

$a_0$ $0.52917721067(12) \times 10^{- 10}$ $\mathrm{m}$ $2.3 \times 10^{- 10}$ Bohr radius $\dfrac{\alpha}{4 \pi R_\infty} = \dfrac{4 \pi \epsilon_0 \hbar^2}{m_\mathrm{e} e^2}$

$E_\mathrm{h}$ $4.359744650(54) \times 10^{- 18}$ $\mathrm{J}$ $1.2 \times 10^{- 8}$ Hartree energy $\dfrac{e^2}{4 \pi \epsilon_0 \alpha_0} = 2 R_\infty h c = \alpha^2 m_\mathrm{e} c^2$

$E_\mathrm{h}$ $27.21138602(17)$ $\mathrm{eV}$ $6.1 \times 10^{- 9}$ Hartree energy $\dfrac{e^2}{4 \pi \epsilon_0 \alpha_0} = 2 R_\infty h c = \alpha^2 m_\mathrm{e} c^2$

$\dfrac{h}{2 m_\mathrm{e}}$ $3.6369475486(17) \times 10^{- 4}$ $\mathrm{m^2 \cdot s^{- 1}}$ $4.5 \times 10^{- 10}$ Quantum of circulation

$\dfrac{h}{m_\mathrm{e}}$ $7.2738950972(33) \times 10^{-4}$ $\mathrm{m^2 \cdot s^{- 1}}$ $4.5 \times 10^{- 10}$ Quantum of circulation

Symbol	Numerical Value	Unit	Relative Standard Uncertainty	`Quantity`
$\alpha$	$7.2973525664(17) \times 10^{- 3}$		$2.3 \times 10^{- 10}$	Fine-structure constant $\dfrac{e^2}{4 \pi \epsilon_0 \hbar c}$
$\dfrac{1}{\alpha}$	$137.035999139(31)$		$2.3 \times 10^{- 10}$	Fine-structure constant $\dfrac{e^2}{4 \pi \epsilon_0 \hbar c}$, inverse fine-structure constant
$R_\infty$	$10973731.568508(65)$	$\mathrm{m^{- 1}}$	$5.9 \times 10^{- 12}$	Rydberg constant $\dfrac{\alpha^2 m_e c}{2 h}$
$R_\infty c$	$3.289841960355(19) \times 10^{15}$	$\mathrm{Hz}$	$5.9 \times 10^{- 12}$	Rydberg constant $\dfrac{\alpha^2 m_e c}{2 h}$
$R_\infty h c$	$2.179872325(27) \times 10^{- 18}$	$\mathrm{J}$	$1.2 \times 10^{- 8}$	Rydberg constant $\dfrac{\alpha^2 m_e c}{2 h}$
$R_\infty h c$	$13.605693009(84)$	$\mathrm{eV}$	$6.1 \times 10^{- 9}$	Rydberg constant $\dfrac{\alpha^2 m_e c}{2 h}$
$a_0$	$0.52917721067(12) \times 10^{- 10}$	$\mathrm{m}$	$2.3 \times 10^{- 10}$	Bohr radius $\dfrac{\alpha}{4 \pi R_\infty} = \dfrac{4 \pi \epsilon_0 \hbar^2}{m_\mathrm{e} e^2}$
$E_\mathrm{h}$	$4.359744650(54) \times 10^{- 18}$	$\mathrm{J}$	$1.2 \times 10^{- 8}$	Hartree energy $\dfrac{e^2}{4 \pi \epsilon_0 \alpha_0} = 2 R_\infty h c = \alpha^2 m_\mathrm{e} c^2$
$E_\mathrm{h}$	$27.21138602(17)$	$\mathrm{eV}$	$6.1 \times 10^{- 9}$	Hartree energy $\dfrac{e^2}{4 \pi \epsilon_0 \alpha_0} = 2 R_\infty h c = \alpha^2 m_\mathrm{e} c^2$
$\dfrac{h}{2 m_\mathrm{e}}$	$3.6369475486(17) \times 10^{- 4}$	$\mathrm{m^2 \cdot s^{- 1}}$	$4.5 \times 10^{- 10}$	Quantum of circulation
$\dfrac{h}{m_\mathrm{e}}$	$7.2738950972(33) \times 10^{-4}$	$\mathrm{m^2 \cdot s^{- 1}}$	$4.5 \times 10^{- 10}$	Quantum of circulation

Electroweak

Symbol Numerical Value Unit Relative Standard Uncertainty Quantity

$\dfrac{G_\mathrm{F}}{(\hbar c)^3}$ $1.1663787(6) \times 10^{- 5}$ $\mathrm{G eV^{- 2}}$ $5.1 \times 10^{- 7}$ Fermi coupling constant

$\sin^2 \theta_\mathrm{W}$ $0.2223(21)$ $9.5 \times 10^{- 3}$ Weak mixing angle $\theta_\mathrm{W}$ (on-shell scheme) $\sin^2 \theta_\mathrm{W} = s_\mathrm{W}^2 \equiv 1 - \left(\dfrac{m_\mathrm{W}}{m_\mathrm{Z}}\right)^2$

Symbol	Numerical Value	Unit	Relative Standard Uncertainty	`Quantity`
$\dfrac{G_\mathrm{F}}{(\hbar c)^3}$	$1.1663787(6) \times 10^{- 5}$	$\mathrm{G eV^{- 2}}$	$5.1 \times 10^{- 7}$	Fermi coupling constant
$\sin^2 \theta_\mathrm{W}$	$0.2223(21)$		$9.5 \times 10^{- 3}$	Weak mixing angle $\theta_\mathrm{W}$ (on-shell scheme) $\sin^2 \theta_\mathrm{W} = s_\mathrm{W}^2 \equiv 1 - \left(\dfrac{m_\mathrm{W}}{m_\mathrm{Z}}\right)^2$

Electron, $\mathrm{e^-}$

Symbol Numerical Value Unit Relative Standard Uncertainty Quantity

$m_\mathrm{e}$ $9.10938356(11) \times 10^{- 31}$ $\mathrm{kg}$ $1.2 \times 10^{- 8}$ Electron mass

$m_\mathrm{e}$ $5.48579909070(16) \times 10^{- 4}$ $\mathrm{u}$ $2.9 \times 10^{- 11}$ Electron mass

$m_\mathrm{e} c^2$ $8.18710565(10) \times 10^{-14}$ $\mathrm{J}$ $1.2 \times 10^{- 8}$ Electron mass, energy equivalent

$m_\mathrm{e} c^2$ $0.5109989461(31)$ $\mathrm{M eV}$ $6.2 \times 10^{- 9}$ Electron mass, energy equivalent

$\dfrac{m_\mathrm{e}}{m_\mu}$ $4.83633170(11) \times 10^{- 3}$ $2.2 \times 10^{- 8}$ Electron-muon mass ratio

$\dfrac{m_\mathrm{e}}{m_\tau}$ $2.87592(26) \times 10^{- 4}$ $9.0 \times 10^{- 5}$ Electron-tau mass ratio

$\dfrac{m_\mathrm{e}}{m_\mathrm{p}}$ $5.44617021352(52) \times 10^{- 4}$ $9.5 \times 10^{- 11}$ Electron-proton mass ratio

$\dfrac{m_\mathrm{e}}{m_\mathrm{n}}$ $5.4386734428(27) \times 10^{- 4}$ $4.9 \times 10^{- 10}$ Electron-neutron mass ratio

$\dfrac{m_\mathrm{e}}{m_\mathrm{d}}$ $2.724437107484(96) \times 10^{- 4}$ $3.5 \times 10^{- 11}$ Electron-deuteron mass ratio

$\dfrac{m_\mathrm{e}}{m_\mathrm{t}}$ $1.819200062203(84) \times 10^{- 4}$ $4.6 \times 10^{- 11}$ Electron-triton mass ratio

$\dfrac{m_\mathrm{e}}{m_\mathrm{h}}$ $1.819543074854(88) \times 10^{- 4}$ $4.9 \times 10^{- 11}$ Electron-helion mass ratio

$\dfrac{m_\mathrm{e}}{m_\alpha}$ $1.370933554798(45) \times 10^{- 4}$ $3.3 \times 10^{- 11}$ Electron to alpha particle mass ratio

$- \dfrac{e}{m_\mathrm{e}}$ $- 1.758820024(11) \times 10^{11}$ $\mathrm{C \cdot kg^{- 1}}$ $6.2 \times 10^{- 9}$ Electron charge to mass quotient

$M(e), M_\mathrm{e}$ $5.48579909070(16) \times 10^{- 7}$ $\mathrm{kg \cdot mol^{- 1}}$ $2.9 \times 10^{- 11}$ Electron molar mass $N_\mathrm{A} m_\mathrm{e}$

$\lambda_\mathrm{C}$ $2.4263102367(11) \times 10^{- 12}$ $\mathrm{m}$ $4.5 \times 10^{- 10}$ Compton wavelength $\dfrac{h}{m_\mathrm{e} c}$

$\bar{\lambda}_\mathrm{C}$ $386.15926764(18) \times 10^{- 15}$ $\mathrm{m}$ $4.5 \times 10^{- 10}$ Compton wavelength $\dfrac{h}{m_\mathrm{e} c}$, $\dfrac{\lambda_\mathrm{C}}{2 \pi} = \alpha a_0 = \dfrac{\alpha^2}{4 \pi R_\infty}$

$r_\mathrm{e}$ $2.8179403227(19) \times 10^{- 15}$ $\mathrm{m}$ $6.8 \times 10^{- 10}$ Classical electron radius $\alpha^2 a_0$

$\sigma_\mathrm{e}$ $0.66524587158(91) \times 10^{- 28}$ $\mathrm{m^2}$ $1.4 \times 10^{- 9}$ Thomson cross section $\dfrac{8 \pi}{3} r_\mathrm{e}^2$

$\mu_\mathrm{e}$ $- 928.4764620(57) \times 10^{- 26}$ $\mathrm{J \cdot T^{- 1}}$ $6.2 \times 10^{- 9}$ Electron magnetic moment

$\dfrac{\mu_\mathrm{e}}{\mu_\mathrm{B}}$ $- 1.00115965218091(26)$ $2.6 \times 10^{- 13}$ Electron magnetic moment, to Bohr magneton ratio

$\dfrac{\mu_\mathrm{e}}{\mu_\mathrm{n}}$ $- 1838.28197234(17)$ $9.5 \times 10^{- 11}$ Electron magnetic moment, to nuclear magneton ratio

$a_\mathrm{e}$ $1.15965218091(26) \times 10^{- 3}$ $2.3 \times 10^{- 10}$ Electron magnetic-moment anomaly $\dfrac{\lvert \mu_\mathrm{e} \rvert}{\mu_\mathrm{B}} - 1$

$g_\mathrm{e}$ $- 2.00231930436182(52)$ $2.6 \times 10^{ -13}$ Electron g-factor $- 2 (1 + a_\mathrm{e})$

$\dfrac{\mu_\mathrm{e}}{\mu_\mu}$ $206.7669880(46)$ $2.2 \times 10^{- 8}$ Electron-muon magnetic-moment ratio

$\dfrac{\mu_\mathrm{e}}{\mu_\mathrm{p}}$ $- 658.2106866(20)$ $3.0 \times 10^{- 9}$ Electron-proton magnetic-moment ratio

$\dfrac{\mu_\mathrm{e}}{\mu_\mathrm{p}’}$ $- 658.2275971(72)$ $1.1 \times 10^{- 8}$ Electron to shielded proton magnetic-moment ratio ($\ce{H_2 O}$, sphere, $\mathrm{25 ^\circ C}$)

$\dfrac{\mu_\mathrm{e}}{\mu_\mathrm{n}}$ $960.92050(23)$ $2.4 \times 10^{- 7}$ Electron-neutron magnetic-moment ratio

$\dfrac{\mu_\mathrm{e}}{\mu_\mathrm{d}}$ $- 2143.923499(12)$ $5.5 \times 10^{- 9}$ Electron-deuteron magnetic-moment ratio

$\dfrac{\mu_\mathrm{e}}{\mu_\mathrm{h}’}$ $864.058257(10)$ $1.2 \times 10^{- 8}$ Electron to shielded helion magnetic-moment ratio (gas, sphere, $\mathrm{25 ^\circ C}$)

$\gamma_\mathrm{e}$ $1.760859644(11) \times 10^{11}$ $\mathrm{s^{- 1} \cdot T^{- 1}}$ $6.2 \times 10^{- 9}$ Electron gyromagnetic ratio $\dfrac{2 \lvert \mu_\mathrm{e} \rvert}{\hbar}$

$\dfrac{\gamma_\mathrm{e}}{2 \pi}$ $28024.95164(17)$ $\mathrm{M Hz \cdot T^{- 1}}$ $6.2 \times 10^{-9}$ Electron gyromagnetic ratio $\dfrac{2 \lvert \mu_\mathrm{e} \rvert}{\hbar}$

Symbol	Numerical Value	Unit	Relative Standard Uncertainty	`Quantity`
$m_\mathrm{e}$	$9.10938356(11) \times 10^{- 31}$	$\mathrm{kg}$	$1.2 \times 10^{- 8}$	Electron mass
$m_\mathrm{e}$	$5.48579909070(16) \times 10^{- 4}$	$\mathrm{u}$	$2.9 \times 10^{- 11}$	Electron mass
$m_\mathrm{e} c^2$	$8.18710565(10) \times 10^{-14}$	$\mathrm{J}$	$1.2 \times 10^{- 8}$	Electron mass, energy equivalent
$m_\mathrm{e} c^2$	$0.5109989461(31)$	$\mathrm{M eV}$	$6.2 \times 10^{- 9}$	Electron mass, energy equivalent
$\dfrac{m_\mathrm{e}}{m_\mu}$	$4.83633170(11) \times 10^{- 3}$		$2.2 \times 10^{- 8}$	Electron-muon mass ratio
$\dfrac{m_\mathrm{e}}{m_\tau}$	$2.87592(26) \times 10^{- 4}$		$9.0 \times 10^{- 5}$	Electron-tau mass ratio
$\dfrac{m_\mathrm{e}}{m_\mathrm{p}}$	$5.44617021352(52) \times 10^{- 4}$		$9.5 \times 10^{- 11}$	Electron-proton mass ratio
$\dfrac{m_\mathrm{e}}{m_\mathrm{n}}$	$5.4386734428(27) \times 10^{- 4}$		$4.9 \times 10^{- 10}$	Electron-neutron mass ratio
$\dfrac{m_\mathrm{e}}{m_\mathrm{d}}$	$2.724437107484(96) \times 10^{- 4}$		$3.5 \times 10^{- 11}$	Electron-deuteron mass ratio
$\dfrac{m_\mathrm{e}}{m_\mathrm{t}}$	$1.819200062203(84) \times 10^{- 4}$		$4.6 \times 10^{- 11}$	Electron-triton mass ratio
$\dfrac{m_\mathrm{e}}{m_\mathrm{h}}$	$1.819543074854(88) \times 10^{- 4}$		$4.9 \times 10^{- 11}$	Electron-helion mass ratio
$\dfrac{m_\mathrm{e}}{m_\alpha}$	$1.370933554798(45) \times 10^{- 4}$		$3.3 \times 10^{- 11}$	Electron to alpha particle mass ratio
$- \dfrac{e}{m_\mathrm{e}}$	$- 1.758820024(11) \times 10^{11}$	$\mathrm{C \cdot kg^{- 1}}$	$6.2 \times 10^{- 9}$	Electron charge to mass quotient
$M(e), M_\mathrm{e}$	$5.48579909070(16) \times 10^{- 7}$	$\mathrm{kg \cdot mol^{- 1}}$	$2.9 \times 10^{- 11}$	Electron molar mass $N_\mathrm{A} m_\mathrm{e}$
$\lambda_\mathrm{C}$	$2.4263102367(11) \times 10^{- 12}$	$\mathrm{m}$	$4.5 \times 10^{- 10}$	Compton wavelength $\dfrac{h}{m_\mathrm{e} c}$
$\bar{\lambda}_\mathrm{C}$	$386.15926764(18) \times 10^{- 15}$	$\mathrm{m}$	$4.5 \times 10^{- 10}$	Compton wavelength $\dfrac{h}{m_\mathrm{e} c}$, $\dfrac{\lambda_\mathrm{C}}{2 \pi} = \alpha a_0 = \dfrac{\alpha^2}{4 \pi R_\infty}$
$r_\mathrm{e}$	$2.8179403227(19) \times 10^{- 15}$	$\mathrm{m}$	$6.8 \times 10^{- 10}$	Classical electron radius $\alpha^2 a_0$
$\sigma_\mathrm{e}$	$0.66524587158(91) \times 10^{- 28}$	$\mathrm{m^2}$	$1.4 \times 10^{- 9}$	Thomson cross section $\dfrac{8 \pi}{3} r_\mathrm{e}^2$
$\mu_\mathrm{e}$	$- 928.4764620(57) \times 10^{- 26}$	$\mathrm{J \cdot T^{- 1}}$	$6.2 \times 10^{- 9}$	Electron magnetic moment
$\dfrac{\mu_\mathrm{e}}{\mu_\mathrm{B}}$	$- 1.00115965218091(26)$		$2.6 \times 10^{- 13}$	Electron magnetic moment, to Bohr magneton ratio
$\dfrac{\mu_\mathrm{e}}{\mu_\mathrm{n}}$	$- 1838.28197234(17)$		$9.5 \times 10^{- 11}$	Electron magnetic moment, to nuclear magneton ratio
$a_\mathrm{e}$	$1.15965218091(26) \times 10^{- 3}$		$2.3 \times 10^{- 10}$	Electron magnetic-moment anomaly $\dfrac{\lvert \mu_\mathrm{e} \rvert}{\mu_\mathrm{B}} - 1$
$g_\mathrm{e}$	$- 2.00231930436182(52)$		$2.6 \times 10^{ -13}$	Electron g-factor $- 2 (1 + a_\mathrm{e})$
$\dfrac{\mu_\mathrm{e}}{\mu_\mu}$	$206.7669880(46)$		$2.2 \times 10^{- 8}$	Electron-muon magnetic-moment ratio
$\dfrac{\mu_\mathrm{e}}{\mu_\mathrm{p}}$	$- 658.2106866(20)$		$3.0 \times 10^{- 9}$	Electron-proton magnetic-moment ratio
$\dfrac{\mu_\mathrm{e}}{\mu_\mathrm{p}’}$	$- 658.2275971(72)$		$1.1 \times 10^{- 8}$	Electron to shielded proton magnetic-moment ratio ($\ce{H_2 O}$, sphere, $\mathrm{25 ^\circ C}$)
$\dfrac{\mu_\mathrm{e}}{\mu_\mathrm{n}}$	$960.92050(23)$		$2.4 \times 10^{- 7}$	Electron-neutron magnetic-moment ratio
$\dfrac{\mu_\mathrm{e}}{\mu_\mathrm{d}}$	$- 2143.923499(12)$		$5.5 \times 10^{- 9}$	Electron-deuteron magnetic-moment ratio
$\dfrac{\mu_\mathrm{e}}{\mu_\mathrm{h}’}$	$864.058257(10)$		$1.2 \times 10^{- 8}$	Electron to shielded helion magnetic-moment ratio (gas, sphere, $\mathrm{25 ^\circ C}$)
$\gamma_\mathrm{e}$	$1.760859644(11) \times 10^{11}$	$\mathrm{s^{- 1} \cdot T^{- 1}}$	$6.2 \times 10^{- 9}$	Electron gyromagnetic ratio $\dfrac{2 \lvert \mu_\mathrm{e} \rvert}{\hbar}$
$\dfrac{\gamma_\mathrm{e}}{2 \pi}$	$28024.95164(17)$	$\mathrm{M Hz \cdot T^{- 1}}$	$6.2 \times 10^{-9}$	Electron gyromagnetic ratio $\dfrac{2 \lvert \mu_\mathrm{e} \rvert}{\hbar}$

Muon, $\mathrm{\mu^-}$

Symbol Numerical Value Unit Relative Standard Uncertainty Quantity

$m_\mu$ $1.883531594(48) \times 10^{- 28}$ $\mathrm{kg}$ $2.5 \times 10^{- 8}$ Muon mass

$m_\mu$ $0.1134289257(25)$ $\mathrm{u}$ $2.2 \times 10^{- 8}$ Muon mass

$m_\mu c^2$ $1.692833774(43) \times 10^{- 11}$ $\mathrm{J}$ $2.5 \times 10^{- 8}$ Muon mass energy, equivalent

$m_\mu c^2$ $105.6583745(24)$ $\mathrm{M eV}$ $2.3 \times 10^{- 8}$ Muon mass energy, equivalent

$\dfrac{m_\mu}{m_\mathrm{e}}$ $206.7682826(46)$ $2.2 \times 10^{- 8}$ Muon-electron mass ratio

$\dfrac{m_\mu}{m_\tau}$ $5.94649(54) \times 10^{- 2}$ $9.0 \times 10^{- 5}$ Muon-tau mass ratio

$\dfrac{m_\mu}{m_\mathrm{p}}$ $0.1126095262(25)$ $2.2 \times 10^{- 8}$ Muon-proton mass ratio

$\dfrac{m_\mu}{m_\mathrm{n}}$ $0.1124545167(25)$ $2.2 \times 10^{- 8}$ Muon-neutron mass ratio

$M(\mu), M_\mu$ $0.1134289257(25) \times 10^{- 3}$ $\mathrm{kg \cdot mol^{- 1}}$ $2.2 \times 10^{- 8}$ Muon molar mass $N_\mathrm{A} m_\mu$

$\lambda_\mathrm{C, \mu}$ $11.73444111(26) \times 10^{- 15}$ $\mathrm{m}$ $2.2 \times 10^{- 8}$ Muon Compton wavelength $\dfrac{h}{m_\mu c}$

$\bar{\lambda}_\mathrm{C, \mu}$ $1.867594308(42) \times 10^{- 15}$ $\mathrm{m}$ $2.2 \times 10^{ -8}$ Muon Compton wavelength $\dfrac{h}{m_\mu c}$, $\dfrac{\lambda_\mathrm{C, \mu}}{2 \pi}$

$\mu_\mu$ $- 4.49044826(10) \times 10^{- 26}$ $\mathrm{J \cdot T^{- 1}}$ $2.3 \times 10^{- 8}$ Muon magnetic moment

$\dfrac{\mu_\mu}{\mu_\mathrm{B}}$ $-4.84197048(11) \times 10^{- 3}$ $2.2 \times 10^{- 8}$ Muon magnetic moment, to Bohr magneton ratio

$\dfrac{\mu_\mu}{\mu_\mathrm{N}}$ $- 8.89059705(20)$ $2.2 \times 10^{- 8}$ Muon magnetic moment, to nuclear magneton ratio

$a_\mathrm{\mu}$ $1.16592089(63) \times 10^{- 3}$ $5.4 \times 10^{ -7}$ Muon magnetic-moment anomaly $\dfrac{\lvert \mu_\mu \rvert}{\dfrac{e \hbar}{2 \mu_\mu}} - 1$

$g_\mu$ $- 2.0023318418(13)$ $6.3 \times 10^{- 10}$ Muon g-factor $- 2 (1 + a_\mu)$

$\dfrac{\mu_\mu}{\mu_\mathrm{p}}$ $- 3.183345142(71)$ $2.2 \times 10^{- 8}$ Muon-proton magnetic-moment ratio

Symbol	Numerical Value	Unit	Relative Standard Uncertainty	`Quantity`
$m_\mu$	$1.883531594(48) \times 10^{- 28}$	$\mathrm{kg}$	$2.5 \times 10^{- 8}$	Muon mass
$m_\mu$	$0.1134289257(25)$	$\mathrm{u}$	$2.2 \times 10^{- 8}$	Muon mass
$m_\mu c^2$	$1.692833774(43) \times 10^{- 11}$	$\mathrm{J}$	$2.5 \times 10^{- 8}$	Muon mass energy, equivalent
$m_\mu c^2$	$105.6583745(24)$	$\mathrm{M eV}$	$2.3 \times 10^{- 8}$	Muon mass energy, equivalent
$\dfrac{m_\mu}{m_\mathrm{e}}$	$206.7682826(46)$		$2.2 \times 10^{- 8}$	Muon-electron mass ratio
$\dfrac{m_\mu}{m_\tau}$	$5.94649(54) \times 10^{- 2}$		$9.0 \times 10^{- 5}$	Muon-tau mass ratio
$\dfrac{m_\mu}{m_\mathrm{p}}$	$0.1126095262(25)$		$2.2 \times 10^{- 8}$	Muon-proton mass ratio
$\dfrac{m_\mu}{m_\mathrm{n}}$	$0.1124545167(25)$		$2.2 \times 10^{- 8}$	Muon-neutron mass ratio
$M(\mu), M_\mu$	$0.1134289257(25) \times 10^{- 3}$	$\mathrm{kg \cdot mol^{- 1}}$	$2.2 \times 10^{- 8}$	Muon molar mass $N_\mathrm{A} m_\mu$
$\lambda_\mathrm{C, \mu}$	$11.73444111(26) \times 10^{- 15}$	$\mathrm{m}$	$2.2 \times 10^{- 8}$	Muon Compton wavelength $\dfrac{h}{m_\mu c}$
$\bar{\lambda}_\mathrm{C, \mu}$	$1.867594308(42) \times 10^{- 15}$	$\mathrm{m}$	$2.2 \times 10^{ -8}$	Muon Compton wavelength $\dfrac{h}{m_\mu c}$, $\dfrac{\lambda_\mathrm{C, \mu}}{2 \pi}$
$\mu_\mu$	$- 4.49044826(10) \times 10^{- 26}$	$\mathrm{J \cdot T^{- 1}}$	$2.3 \times 10^{- 8}$	Muon magnetic moment
$\dfrac{\mu_\mu}{\mu_\mathrm{B}}$	$-4.84197048(11) \times 10^{- 3}$		$2.2 \times 10^{- 8}$	Muon magnetic moment, to Bohr magneton ratio
$\dfrac{\mu_\mu}{\mu_\mathrm{N}}$	$- 8.89059705(20)$		$2.2 \times 10^{- 8}$	Muon magnetic moment, to nuclear magneton ratio
$a_\mathrm{\mu}$	$1.16592089(63) \times 10^{- 3}$		$5.4 \times 10^{ -7}$	Muon magnetic-moment anomaly $\dfrac{\lvert \mu_\mu \rvert}{\dfrac{e \hbar}{2 \mu_\mu}} - 1$
$g_\mu$	$- 2.0023318418(13)$		$6.3 \times 10^{- 10}$	Muon g-factor $- 2 (1 + a_\mu)$
$\dfrac{\mu_\mu}{\mu_\mathrm{p}}$	$- 3.183345142(71)$		$2.2 \times 10^{- 8}$	Muon-proton magnetic-moment ratio

Tau, $\tau^-$

Symbol Numerical Value Unit Relative Standard Uncertainty Quantity

$m_\tau$ $3.16747(29) \times 10^{- 27}$ $\mathrm{kg}$ $9.0 \times 10^{- 5}$ Tau mass

$m_\tau$ $1.90749(17)$ $\mathrm{u}$ $9.0 \times 10^{- 5}$ Tau mass

$m_\tau c^2$ $2.84678(26) \times 10^{- 10}$ $\mathrm{J}$ $9.0 \times 10^{- 5}$ Tau mass, energy equivalent

$m_\tau c^2$ $1776.82(16)$ $\mathrm{M eV}$ $9.0 \times 10^{- 5}$ Tau mass, energy equivalent

$\dfrac{m_\tau}{m_\mathrm{e}}$ $3477.15(31)$ $9.0 \times 10^{- 5}$ Tau-electron mass ratio

$\dfrac{m_\tau}{m_\mu}$ $16.8167(15)$ $9.0 \times 10^{- 5}$ Tau-muon mass ratio

$\dfrac{m_\tau}{m_\mathrm{p}}$ $1.89372(17)$ $9.0 \times 10^{- 5}$ Tau-proton mass ratio

$\dfrac{m_\tau}{m_\mathrm{n}}$ $1.89111(17)$ $9.0 \times 10^{- 5}$ Tau-neutron mass ratio

$M(\tau), M_\tau$ $1.90749(17) \times 10^{- 3}$ $\mathrm{kg \cdot mol^{- 1}}$ $9.0 \times 10^{- 5}$ Tau molar mass $N_\mathrm{A} m_\tau$

$\lambda_\mathrm{C, \tau}$ $0.697787(63) \times 10^{- 15}$ $\mathrm{m}$ $9.0 \times 10^{- 5}$ Tau Compton wavelength $\dfrac{h}{m_\tau c}$

$\bar{\lambda}_{C, \tau}$ $0.111056(10) \times 10^{- 15}$ $\mathrm{m}$ $9.0 \times 10^{ -5}$ Tau Compton wavelength $\dfrac{h}{m_\tau c}$, $\dfrac{\lambda_\mathrm{C, \tau}}{2 \pi}$

Symbol	Numerical Value	Unit	Relative Standard Uncertainty	`Quantity`
$m_\tau$	$3.16747(29) \times 10^{- 27}$	$\mathrm{kg}$	$9.0 \times 10^{- 5}$	Tau mass
$m_\tau$	$1.90749(17)$	$\mathrm{u}$	$9.0 \times 10^{- 5}$	Tau mass
$m_\tau c^2$	$2.84678(26) \times 10^{- 10}$	$\mathrm{J}$	$9.0 \times 10^{- 5}$	Tau mass, energy equivalent
$m_\tau c^2$	$1776.82(16)$	$\mathrm{M eV}$	$9.0 \times 10^{- 5}$	Tau mass, energy equivalent
$\dfrac{m_\tau}{m_\mathrm{e}}$	$3477.15(31)$		$9.0 \times 10^{- 5}$	Tau-electron mass ratio
$\dfrac{m_\tau}{m_\mu}$	$16.8167(15)$		$9.0 \times 10^{- 5}$	Tau-muon mass ratio
$\dfrac{m_\tau}{m_\mathrm{p}}$	$1.89372(17)$		$9.0 \times 10^{- 5}$	Tau-proton mass ratio
$\dfrac{m_\tau}{m_\mathrm{n}}$	$1.89111(17)$		$9.0 \times 10^{- 5}$	Tau-neutron mass ratio
$M(\tau), M_\tau$	$1.90749(17) \times 10^{- 3}$	$\mathrm{kg \cdot mol^{- 1}}$	$9.0 \times 10^{- 5}$	Tau molar mass $N_\mathrm{A} m_\tau$
$\lambda_\mathrm{C, \tau}$	$0.697787(63) \times 10^{- 15}$	$\mathrm{m}$	$9.0 \times 10^{- 5}$	Tau Compton wavelength $\dfrac{h}{m_\tau c}$
$\bar{\lambda}_{C, \tau}$	$0.111056(10) \times 10^{- 15}$	$\mathrm{m}$	$9.0 \times 10^{ -5}$	Tau Compton wavelength $\dfrac{h}{m_\tau c}$, $\dfrac{\lambda_\mathrm{C, \tau}}{2 \pi}$

Proton, $\mathrm{p}$

Symbol Numerical Value Unit Relative Standard Uncertainty Quantity

$m_\mathrm{p}$ $1.672621898(21) \times 10^{- 27}$ $\mathrm{kg}$ $1.2 \times 10^{- 8}$ Proton mass

$m_\mathrm{p}$ $1.007276466879(91)$ $\mathrm{u}$ $9.0 \times 10^{- 11}$ Proton mass

$m_\mathrm{p} c^2$ $1.503277593(18) \times 10^{- 10}$ $\mathrm{J}$ $1.2 \times 10^{- 8}$ Proton mass, energy equivalent

$m_\mathrm{p} c^2$ $938.2720813(58)$ $\mathrm{M eV}$ $6.2 \times 10^{- 9}$ Proton mass, energy equivalent

$\dfrac{m_\mathrm{p}}{m_\mathrm{e}}$ $1836.15267389(17)$ $9.5 \times 10^{- 11}$ Proton-electron mass ratio

$\dfrac{m_\mathrm{p}}{m_\mu}$ $8.88024338(20)$ $2.2 \times 10^{- 8}$ Proton-muon mass ratio

$\dfrac{m_\mathrm{p}}{m_\tau}$ $0.528063(48)$ $9.0 \times 10^{- 5}$ Proton-tau mass ratio

$\dfrac{m_\mathrm{p}}{m_\mathrm{n}}$ $0.99862347844(51)$ $5.1 \times 10^{- 10}$ Proton-neutron mass ratio

$\dfrac{e}{m_\mathrm{p}}$ $9.578833226(59) \times 10^7$ $\mathrm{C \cdot kg^{- 1}}$ $6.2 \times 10^{- 9}$ Proton charge-to-mass quotient

$M (p), M_\mathrm{p}$ $1.007276466879(91) \times 10^{- 3}$ $\mathrm{kg \cdot mol^{- 1}}$ $9.0 \times 10^{- 11}$ Proton molar mass $N_\mathrm{A} m_\mathrm{p}$

$\lambda_\mathrm{C, p}$ $1.32140985396(61) \times 10^{- 15}$ $\mathrm{m}$ $4.6 \times 10^{- 10}$ Proton Compton wavelength $\dfrac{h}{m_\mathrm{p} c}$

$\bar{\lambda}_\mathrm{C, p}$ $0.210308910109(97) \times 10^{- 15}$ $\mathrm{m}$ $4.6 \times 10^{- 10}$ Proton Compton wavelength $\dfrac{h}{m_\mathrm{p} c}$, $\dfrac{\lambda_\mathrm{C, p}}{2 \pi}$

$r_\mathrm{p}$ $0.8751(61) \times 10^{- 15}$ $\mathrm{m}$ $7.0 \times 10^{- 3}$ Proton rms charge radius

$\mu_\mathrm{p}$ $1.4106067873(97) \times 10^{- 26}$ $\mathrm{J \cdot T^{- 1}}$ $6.9 \times 10^{- 9}$ Proton magnetic moment

$\dfrac{\mu_\mathrm{p}}{\mu_\mathrm{B}}$ $1.5210322053(46) \times 10^{- 3}$ $3.0 \times 10^{- 9}$ Proton magnetic moment, to Bohr magneton ratio

$\dfrac{\mu_\mathrm{p}}{\mu_\mathrm{n}}$ $2.7928473508(85)$ $3.0 \times 10^{- 9}$ Proton magnetic moment, to Bohr magneton ratio

$g_\mathrm{p}$ $5.585694702(17)$ $3.0 \times 10^{- 9}$ Proton g-factor $\dfrac{2 \mu_\mathrm{p}}{\mu_\mathrm{N}}$

$\dfrac{\mu_\mathrm{p}}{\mu_\mathrm{n}}$ $- 1.45989805(34)$ $2.4 \times 10^{- 7}$ Proton-neutron magnetic-moment ratio

$\mu_\mathrm{p}’$ $1.410570547(18) \times 10^{- 26}$ $\mathrm{J \cdot T^{- 1}}$ $1.3 \times 10^{- 8}$ Shielded proton magnetic moment ($\ce{H_2 O}$, sphere, $\mathrm{25 ^\circ C}$)

$\dfrac{\mu_\mathrm{p}’}{\mu_\mathrm{B}}$ $1.520993128(17) \times 10^{- 3}$ $1.1 \times 10^{- 8}$ Shielded proton magnetic moment ($\ce{H_2 O}$, sphere, $\mathrm{25 ^\circ C}$), to Bohr magneton ratio

$\dfrac{\mu_\mathrm{p}’}{\mu_\mathrm{N}}$ $2.792775600(30)$ $1.1 \times 10^{- 8}$ Shielded proton magnetic moment ($\ce{H_2 O}$, sphere, $\mathrm{25 ^\circ C}$), to nuclear magneton ratio

$\sigma_\mathrm{p}’$ $25.691(11) \times 10^{- 6}$ $4.4 \times 10^{- 4}$ Proton magnetic shielding correction $1 - \dfrac{\mu_\mathrm{p}’}{\mu_\mathrm{p}}$ ($\ce{H_2 O}$, sphere, $\mathrm{25 ^\circ C}$)

$\gamma_\mathrm{p}$ $2.675221900(18) \times 10^8$ $\mathrm{s^{- 1} \cdot T^{- 1}}$ $6.9 \times 10^{- 9}$ Proton gyromagnetic ratio $\dfrac{2 \mu_\mathrm{p}}{\hbar}$

$\dfrac{\gamma_\mathrm{p}}{2 \pi}$ $42.57747892(29)$ $\mathrm{M Hz \cdot T^{- 1}}$ $6.9 \times 10^{- 9}$ Proton gyromagnetic ratio $\dfrac{2 \mu_\mathrm{p}}{\hbar}$

$\gamma_\mathrm{p}’$ $2.675153171(33) \times 10^8$ $\mathrm{s^{- 1} \cdot T^{- 1}}$ $1.3 \times 10^{- 8}$ Shielded proton gyromagnetic ratio $\dfrac{2 \mu_\mathrm{p}’}{\hbar}$ ($\ce{H_2 O}$, sphere, $\mathrm{25 ^\circ C}$)

$\dfrac{\gamma_\mathrm{p}’}{2 \pi}$ $42.57638507(53)$ $\mathrm{M Hz \cdot T^{- 1}}$ $1.3 \times 10^{- 8}$ Shielded proton gyromagnetic ratio $\dfrac{2 \mu_\mathrm{p}’}{\hbar}$ ($\ce{H_2 O}$, sphere, $\mathrm{25 ^\circ C}$)

Symbol	Numerical Value	Unit	Relative Standard Uncertainty	`Quantity`
$m_\mathrm{p}$	$1.672621898(21) \times 10^{- 27}$	$\mathrm{kg}$	$1.2 \times 10^{- 8}$	Proton mass
$m_\mathrm{p}$	$1.007276466879(91)$	$\mathrm{u}$	$9.0 \times 10^{- 11}$	Proton mass
$m_\mathrm{p} c^2$	$1.503277593(18) \times 10^{- 10}$	$\mathrm{J}$	$1.2 \times 10^{- 8}$	Proton mass, energy equivalent
$m_\mathrm{p} c^2$	$938.2720813(58)$	$\mathrm{M eV}$	$6.2 \times 10^{- 9}$	Proton mass, energy equivalent
$\dfrac{m_\mathrm{p}}{m_\mathrm{e}}$	$1836.15267389(17)$		$9.5 \times 10^{- 11}$	Proton-electron mass ratio
$\dfrac{m_\mathrm{p}}{m_\mu}$	$8.88024338(20)$		$2.2 \times 10^{- 8}$	Proton-muon mass ratio
$\dfrac{m_\mathrm{p}}{m_\tau}$	$0.528063(48)$		$9.0 \times 10^{- 5}$	Proton-tau mass ratio
$\dfrac{m_\mathrm{p}}{m_\mathrm{n}}$	$0.99862347844(51)$		$5.1 \times 10^{- 10}$	Proton-neutron mass ratio
$\dfrac{e}{m_\mathrm{p}}$	$9.578833226(59) \times 10^7$	$\mathrm{C \cdot kg^{- 1}}$	$6.2 \times 10^{- 9}$	Proton charge-to-mass quotient
$M (p), M_\mathrm{p}$	$1.007276466879(91) \times 10^{- 3}$	$\mathrm{kg \cdot mol^{- 1}}$	$9.0 \times 10^{- 11}$	Proton molar mass $N_\mathrm{A} m_\mathrm{p}$
$\lambda_\mathrm{C, p}$	$1.32140985396(61) \times 10^{- 15}$	$\mathrm{m}$	$4.6 \times 10^{- 10}$	Proton Compton wavelength $\dfrac{h}{m_\mathrm{p} c}$
$\bar{\lambda}_\mathrm{C, p}$	$0.210308910109(97) \times 10^{- 15}$	$\mathrm{m}$	$4.6 \times 10^{- 10}$	Proton Compton wavelength $\dfrac{h}{m_\mathrm{p} c}$, $\dfrac{\lambda_\mathrm{C, p}}{2 \pi}$
$r_\mathrm{p}$	$0.8751(61) \times 10^{- 15}$	$\mathrm{m}$	$7.0 \times 10^{- 3}$	Proton rms charge radius
$\mu_\mathrm{p}$	$1.4106067873(97) \times 10^{- 26}$	$\mathrm{J \cdot T^{- 1}}$	$6.9 \times 10^{- 9}$	Proton magnetic moment
$\dfrac{\mu_\mathrm{p}}{\mu_\mathrm{B}}$	$1.5210322053(46) \times 10^{- 3}$		$3.0 \times 10^{- 9}$	Proton magnetic moment, to Bohr magneton ratio
$\dfrac{\mu_\mathrm{p}}{\mu_\mathrm{n}}$	$2.7928473508(85)$		$3.0 \times 10^{- 9}$	Proton magnetic moment, to Bohr magneton ratio
$g_\mathrm{p}$	$5.585694702(17)$		$3.0 \times 10^{- 9}$	Proton g-factor $\dfrac{2 \mu_\mathrm{p}}{\mu_\mathrm{N}}$
$\dfrac{\mu_\mathrm{p}}{\mu_\mathrm{n}}$	$- 1.45989805(34)$		$2.4 \times 10^{- 7}$	Proton-neutron magnetic-moment ratio
$\mu_\mathrm{p}’$	$1.410570547(18) \times 10^{- 26}$	$\mathrm{J \cdot T^{- 1}}$	$1.3 \times 10^{- 8}$	Shielded proton magnetic moment ($\ce{H_2 O}$, sphere, $\mathrm{25 ^\circ C}$)
$\dfrac{\mu_\mathrm{p}’}{\mu_\mathrm{B}}$	$1.520993128(17) \times 10^{- 3}$		$1.1 \times 10^{- 8}$	Shielded proton magnetic moment ($\ce{H_2 O}$, sphere, $\mathrm{25 ^\circ C}$), to Bohr magneton ratio
$\dfrac{\mu_\mathrm{p}’}{\mu_\mathrm{N}}$	$2.792775600(30)$		$1.1 \times 10^{- 8}$	Shielded proton magnetic moment ($\ce{H_2 O}$, sphere, $\mathrm{25 ^\circ C}$), to nuclear magneton ratio
$\sigma_\mathrm{p}’$	$25.691(11) \times 10^{- 6}$		$4.4 \times 10^{- 4}$	Proton magnetic shielding correction $1 - \dfrac{\mu_\mathrm{p}’}{\mu_\mathrm{p}}$ ($\ce{H_2 O}$, sphere, $\mathrm{25 ^\circ C}$)
$\gamma_\mathrm{p}$	$2.675221900(18) \times 10^8$	$\mathrm{s^{- 1} \cdot T^{- 1}}$	$6.9 \times 10^{- 9}$	Proton gyromagnetic ratio $\dfrac{2 \mu_\mathrm{p}}{\hbar}$
$\dfrac{\gamma_\mathrm{p}}{2 \pi}$	$42.57747892(29)$	$\mathrm{M Hz \cdot T^{- 1}}$	$6.9 \times 10^{- 9}$	Proton gyromagnetic ratio $\dfrac{2 \mu_\mathrm{p}}{\hbar}$
$\gamma_\mathrm{p}’$	$2.675153171(33) \times 10^8$	$\mathrm{s^{- 1} \cdot T^{- 1}}$	$1.3 \times 10^{- 8}$	Shielded proton gyromagnetic ratio $\dfrac{2 \mu_\mathrm{p}’}{\hbar}$ ($\ce{H_2 O}$, sphere, $\mathrm{25 ^\circ C}$)
$\dfrac{\gamma_\mathrm{p}’}{2 \pi}$	$42.57638507(53)$	$\mathrm{M Hz \cdot T^{- 1}}$	$1.3 \times 10^{- 8}$	Shielded proton gyromagnetic ratio $\dfrac{2 \mu_\mathrm{p}’}{\hbar}$ ($\ce{H_2 O}$, sphere, $\mathrm{25 ^\circ C}$)

Neutron, $\mathrm{n}$

Symbol Numerical Value Unit Relative Standard Uncertainty Quantity

$m_\mathrm{n}$ $1.674927471(21) \times 10^{- 27}$ $\mathrm{kg}$ $1.2 \times 10^{- 8}$ Neutron mass

$m_\mathrm{n}$ $1.00866491588(49)$ $\mathrm{u}$ $4.9 \times 10^{- 10}$ Neutron mass

$m_\mathrm{n} c^2$ $1.505349739(19) \times 10^{- 10}$ $\mathrm{J}$ $1.2 \times 10^{- 8}$ Neutron mass energy equivalent

$m_\mathrm{n} c^2$ $939.5654133(58)$ $\mathrm{M eV}$ $6.2 \times 10^{- 9}$ Neutron mass, energy equivalent

$\dfrac{m_\mathrm{n}}{m_\mathrm{e}}$ $1838.68366158(90)$ $4.9 \times 10^{- 10}$ Neutron-electron mass ratio

$\dfrac{m_\mathrm{n}}{m_\mu}$ $8.89248408(20)$ $2.2 \times 10^{- 8}$ Neutron-muon mass ratio

$\dfrac{m_\mathrm{n}}{m_\tau}$ $0.528790(48)$ $9.0 \times 10^{- 5}$ Neutron-tau mass ratio

$\dfrac{m_\mathrm{n}}{m_\mathrm{p}}$ $1.00137841898(51)$ $5.1 \times 10^{- 10}$ Neutron-proton mass ratio

$m_\mathrm{n} - m_\mathrm{p}$ $2.30557377(85) \times 10^{- 30}$ $\mathrm{kg}$ $3.7 \times 10^{- 7}$ Neutron-proton mass difference

$m_\mathrm{n} - m_\mathrm{p}$ $0.00138844900(51)$ $\mathrm{u}$ $3.7 \times 10^{- 7}$ Neutron-proton mass difference

$(m_\mathrm{n} - m_\mathrm{p}) c^2$ $2.07214637(76) \times 10^{- 13}$ $\mathrm{J}$ $3.7 \times 10^{- 7}$ Neutron-proton mass difference, energy equivalent

$(m_\mathrm{n} - m_\mathrm{p}) c^2$ $1.29333205(48)$ $\mathrm{M eV}$ $3.7 \times 10^{- 7}$ Neutron-proton mass difference, energy equivalent

$M (n), M_\mathrm{n}$ $1.00866491588(49) \times 10^{- 3}$ $\mathrm{kg \cdot mol^{- 1}}$ $4.9 \times 10^{- 10}$ Neutron molar mass $N_\mathrm{A} m_\mathrm{n}$

$\lambda_\mathrm{C, n}$ $1.31959090481(88) \times 10^{- 15}$ $\mathrm{m}$ $6.7 \times 10^{- 10}$ Neutron Compton wavelength $\dfrac{h}{m_\mathrm{n} c}$

$\bar{\lambda}_\mathrm{C, n}$ $0.21001941536(14) \times 10^{- 15}$ $\mathrm{m}$ $6.7 \times 10^{- 10}$ Neutron Compton wavelength $\dfrac{h}{m_\mathrm{n} c}$, $\dfrac{\lambda_\mathrm{C, n}}{2 \pi}$

$\mu_\mathrm{n}$ $- 0.96623650(23) \times 10^{- 26}$ $\mathrm{J \cdot T^{- 1}}$ $2.4 \times 10^{ -7}$ Neutron magnetic moment

$\dfrac{\mu_\mathrm{n}}{\mu_\mathrm{B}}$ $- 1.04187563(25) \times 10^{- 3}$ $2.4 \times 10^{- 7}$ Neutron magnetic moment, to Bohr magneton ratio

$\dfrac{\mu_\mathrm{n}}{\mu_\mathrm{N}}$ $- 1.91304273(45)$ $2.4 \times 10^{- 7}$ Neutron magnetic moment, to nuclear magneton ratio

$g_\mathrm{n}$ $- 3.82608545(90)$ $2.4 \times 10^{- 7}$ Neutron g-factor $\dfrac{2 \mu_\mathrm{n}}{\mu_\mathrm{N}}$

$\dfrac{\mu_\mathrm{n}}{\mu_\mathrm{e}}$ $1.04066882(25) \times 10^{- 3}$ $2.4 \times 10^{- 7}$ Neutron-electron magnetic-moment ratio

$\dfrac{\mu_\mathrm{n}}{\mu_\mathrm{p}}$ $- 0.68497934(16)$ $2.4 \times 10^{- 7}$ Neutron-proton magnetic-moment ratio

$\dfrac{\mu_\mathrm{n}}{\mu_\mathrm{p}’}$ $- 0.68499694(16)$ $2. 4\times 10^{- 7}$ Neutron to shielded proton magnetic-moment ratio ($\ce{H_0 O}$, sphere, $\mathrm{25 ^\circ C}$)

$\gamma_\mathrm{n}$ $1.83247172(43) \times 10^8$ $\mathrm{s^{- 1} \cdot T^{- 1}}$ $2.4 \times 10^{- 7}$ Neutron gyromagnetic ratio $\dfrac{2 \lvert \mu_\mathrm{n} \rvert}{\hbar}$

$\dfrac{\gamma_\mathrm{n}}{2 \pi}$ $29.1646933(69)$ $\mathrm{M Hz \cdot T^{- 1}}$ $2.4 \times 10^{- 7}$ Neutron gyromagnetic ratio $\dfrac{2 \lvert \mu_\mathrm{n} \rvert}{\hbar}$

Symbol	Numerical Value	Unit	Relative Standard Uncertainty	`Quantity`
$m_\mathrm{n}$	$1.674927471(21) \times 10^{- 27}$	$\mathrm{kg}$	$1.2 \times 10^{- 8}$	Neutron mass
$m_\mathrm{n}$	$1.00866491588(49)$	$\mathrm{u}$	$4.9 \times 10^{- 10}$	Neutron mass
$m_\mathrm{n} c^2$	$1.505349739(19) \times 10^{- 10}$	$\mathrm{J}$	$1.2 \times 10^{- 8}$	Neutron mass energy equivalent
$m_\mathrm{n} c^2$	$939.5654133(58)$	$\mathrm{M eV}$	$6.2 \times 10^{- 9}$	Neutron mass, energy equivalent
$\dfrac{m_\mathrm{n}}{m_\mathrm{e}}$	$1838.68366158(90)$		$4.9 \times 10^{- 10}$	Neutron-electron mass ratio
$\dfrac{m_\mathrm{n}}{m_\mu}$	$8.89248408(20)$		$2.2 \times 10^{- 8}$	Neutron-muon mass ratio
$\dfrac{m_\mathrm{n}}{m_\tau}$	$0.528790(48)$		$9.0 \times 10^{- 5}$	Neutron-tau mass ratio
$\dfrac{m_\mathrm{n}}{m_\mathrm{p}}$	$1.00137841898(51)$		$5.1 \times 10^{- 10}$	Neutron-proton mass ratio
$m_\mathrm{n} - m_\mathrm{p}$	$2.30557377(85) \times 10^{- 30}$	$\mathrm{kg}$	$3.7 \times 10^{- 7}$	Neutron-proton mass difference
$m_\mathrm{n} - m_\mathrm{p}$	$0.00138844900(51)$	$\mathrm{u}$	$3.7 \times 10^{- 7}$	Neutron-proton mass difference
$(m_\mathrm{n} - m_\mathrm{p}) c^2$	$2.07214637(76) \times 10^{- 13}$	$\mathrm{J}$	$3.7 \times 10^{- 7}$	Neutron-proton mass difference, energy equivalent
$(m_\mathrm{n} - m_\mathrm{p}) c^2$	$1.29333205(48)$	$\mathrm{M eV}$	$3.7 \times 10^{- 7}$	Neutron-proton mass difference, energy equivalent
$M (n), M_\mathrm{n}$	$1.00866491588(49) \times 10^{- 3}$	$\mathrm{kg \cdot mol^{- 1}}$	$4.9 \times 10^{- 10}$	Neutron molar mass $N_\mathrm{A} m_\mathrm{n}$
$\lambda_\mathrm{C, n}$	$1.31959090481(88) \times 10^{- 15}$	$\mathrm{m}$	$6.7 \times 10^{- 10}$	Neutron Compton wavelength $\dfrac{h}{m_\mathrm{n} c}$
$\bar{\lambda}_\mathrm{C, n}$	$0.21001941536(14) \times 10^{- 15}$	$\mathrm{m}$	$6.7 \times 10^{- 10}$	Neutron Compton wavelength $\dfrac{h}{m_\mathrm{n} c}$, $\dfrac{\lambda_\mathrm{C, n}}{2 \pi}$
$\mu_\mathrm{n}$	$- 0.96623650(23) \times 10^{- 26}$	$\mathrm{J \cdot T^{- 1}}$	$2.4 \times 10^{ -7}$	Neutron magnetic moment
$\dfrac{\mu_\mathrm{n}}{\mu_\mathrm{B}}$	$- 1.04187563(25) \times 10^{- 3}$		$2.4 \times 10^{- 7}$	Neutron magnetic moment, to Bohr magneton ratio
$\dfrac{\mu_\mathrm{n}}{\mu_\mathrm{N}}$	$- 1.91304273(45)$		$2.4 \times 10^{- 7}$	Neutron magnetic moment, to nuclear magneton ratio
$g_\mathrm{n}$	$- 3.82608545(90)$		$2.4 \times 10^{- 7}$	Neutron g-factor $\dfrac{2 \mu_\mathrm{n}}{\mu_\mathrm{N}}$
$\dfrac{\mu_\mathrm{n}}{\mu_\mathrm{e}}$	$1.04066882(25) \times 10^{- 3}$		$2.4 \times 10^{- 7}$	Neutron-electron magnetic-moment ratio
$\dfrac{\mu_\mathrm{n}}{\mu_\mathrm{p}}$	$- 0.68497934(16)$		$2.4 \times 10^{- 7}$	Neutron-proton magnetic-moment ratio
$\dfrac{\mu_\mathrm{n}}{\mu_\mathrm{p}’}$	$- 0.68499694(16)$		$2. 4\times 10^{- 7}$	Neutron to shielded proton magnetic-moment ratio ($\ce{H_0 O}$, sphere, $\mathrm{25 ^\circ C}$)
$\gamma_\mathrm{n}$	$1.83247172(43) \times 10^8$	$\mathrm{s^{- 1} \cdot T^{- 1}}$	$2.4 \times 10^{- 7}$	Neutron gyromagnetic ratio $\dfrac{2 \lvert \mu_\mathrm{n} \rvert}{\hbar}$
$\dfrac{\gamma_\mathrm{n}}{2 \pi}$	$29.1646933(69)$	$\mathrm{M Hz \cdot T^{- 1}}$	$2.4 \times 10^{- 7}$	Neutron gyromagnetic ratio $\dfrac{2 \lvert \mu_\mathrm{n} \rvert}{\hbar}$

Deuteron, $\mathrm{d}$

Symbol Numerical Value Unit Relative Standard Uncertainty Quantity

$m_\mathrm{d}$ $3.343583719(41) \times 10^{- 27}$ $\mathrm{kg}$ $1.2 \times 10^{- 8}$ Deuteron mass

$m_\mathrm{d}$ $2.013553212745(40)$ $\mathrm{u}$ $2.0 \times 10^{- 11}$ Deuteron mass

$m_\mathrm{d} c^2$ $3.005063183(37) \times 10^{- 10}$ $\mathrm{J}$ $1.2 \times 10^{- 8}$ Deuteron mass, energy equivalent

$m_\mathrm{d} c^2$ $1875.612928(12)$ $\mathrm{M eV}$ $6.2 \times 10^{- 9}$ Deuteron mass, energy equivalent

$\dfrac{m_\mathrm{d}}{m_\mathrm{e}}$ $3670.48296785(13)$ $3.5 \times 10^{- 11}$ Deuteron-electron mass ratio

$\dfrac{m_\mathrm{d}}{m_\mathrm{p}}$ $1.99900750087(19)$ $9.3 \times 10^{- 11}$ Deuteron-proton mass ratio

$M (d), M_\mathrm{d}$ $2.013553212745(40) \times 10^{- 3}$ $\mathrm{kg \cdot mol^{- 1}}$ $2.0 \times 10^{- 11}$ Deuteron molar mass $N_\mathrm{A} m_\mathrm{d}$

$r_\mathrm{d}$ $2.1413(25) \times 10^{- 15}$ $\mathrm{m}$ $1.2 \times 10^{- 3}$ Deuteron rms charge radius

$\mu_\mathrm{d}$ $0.4330735040(36) \times 10^{- 26}$ $\mathrm{J \cdot T^{- 1}}$ $8.3 \times 10^{- 9}$ Deuteron magnetic moment

$\dfrac{\mu_\mathrm{d}}{\mu_\mathrm{B}}$ $0.4669754554(26) \times 10^{- 3}$ $5.5 \times 10^{- 9}$ Deuteron magnetic moment, to Bohr magneton ratio

$\dfrac{\mu_\mathrm{d}}{\mu_\mathrm{N}}$ $0.8574382311(48)$ $5.5 \times 10^{- 9}$ Deuteron magnetic moment, to nuclear magneton ratio

$g_\mathrm{d}$ $0.8574382311(48)$ $5.5 \times 10^{- 9}$ Deuteron g-factor $\dfrac{\mu_\mathrm{d}}{\mu_\mathrm{N}}$

$\dfrac{\mu_\mathrm{d}}{\mu_\mathrm{e}}$ $- 4.664345535(26) \times 10^{- 4}$ $5.5 \times 10^{- 9}$ Deuteron-electron magnetic-moment ratio

$\dfrac{\mu_\mathrm{d}}{\mu_\mathrm{p}}$ $0.3070122077(15)$ $5.0 \times 10^{- 9}$ Deuteron-proton magnetic-moment ratio

$\dfrac{\mu_\mathrm{d}}{\mu_\mathrm{n}}$ $- 0.44820652(11)$ $2.4 \times 10^{- 7}$ Deuteron-neutron magnetic-moment ratio

Symbol	Numerical Value	Unit	Relative Standard Uncertainty	`Quantity`
$m_\mathrm{d}$	$3.343583719(41) \times 10^{- 27}$	$\mathrm{kg}$	$1.2 \times 10^{- 8}$	Deuteron mass
$m_\mathrm{d}$	$2.013553212745(40)$	$\mathrm{u}$	$2.0 \times 10^{- 11}$	Deuteron mass
$m_\mathrm{d} c^2$	$3.005063183(37) \times 10^{- 10}$	$\mathrm{J}$	$1.2 \times 10^{- 8}$	Deuteron mass, energy equivalent
$m_\mathrm{d} c^2$	$1875.612928(12)$	$\mathrm{M eV}$	$6.2 \times 10^{- 9}$	Deuteron mass, energy equivalent
$\dfrac{m_\mathrm{d}}{m_\mathrm{e}}$	$3670.48296785(13)$		$3.5 \times 10^{- 11}$	Deuteron-electron mass ratio
$\dfrac{m_\mathrm{d}}{m_\mathrm{p}}$	$1.99900750087(19)$		$9.3 \times 10^{- 11}$	Deuteron-proton mass ratio
$M (d), M_\mathrm{d}$	$2.013553212745(40) \times 10^{- 3}$	$\mathrm{kg \cdot mol^{- 1}}$	$2.0 \times 10^{- 11}$	Deuteron molar mass $N_\mathrm{A} m_\mathrm{d}$
$r_\mathrm{d}$	$2.1413(25) \times 10^{- 15}$	$\mathrm{m}$	$1.2 \times 10^{- 3}$	Deuteron rms charge radius
$\mu_\mathrm{d}$	$0.4330735040(36) \times 10^{- 26}$	$\mathrm{J \cdot T^{- 1}}$	$8.3 \times 10^{- 9}$	Deuteron magnetic moment
$\dfrac{\mu_\mathrm{d}}{\mu_\mathrm{B}}$	$0.4669754554(26) \times 10^{- 3}$		$5.5 \times 10^{- 9}$	Deuteron magnetic moment, to Bohr magneton ratio
$\dfrac{\mu_\mathrm{d}}{\mu_\mathrm{N}}$	$0.8574382311(48)$		$5.5 \times 10^{- 9}$	Deuteron magnetic moment, to nuclear magneton ratio
$g_\mathrm{d}$	$0.8574382311(48)$		$5.5 \times 10^{- 9}$	Deuteron g-factor $\dfrac{\mu_\mathrm{d}}{\mu_\mathrm{N}}$
$\dfrac{\mu_\mathrm{d}}{\mu_\mathrm{e}}$	$- 4.664345535(26) \times 10^{- 4}$		$5.5 \times 10^{- 9}$	Deuteron-electron magnetic-moment ratio
$\dfrac{\mu_\mathrm{d}}{\mu_\mathrm{p}}$	$0.3070122077(15)$		$5.0 \times 10^{- 9}$	Deuteron-proton magnetic-moment ratio
$\dfrac{\mu_\mathrm{d}}{\mu_\mathrm{n}}$	$- 0.44820652(11)$		$2.4 \times 10^{- 7}$	Deuteron-neutron magnetic-moment ratio

Triton, $\mathrm{t}$

Symbol Numerical Value Unit Relative Standard Uncertainty Quantity

$m_\mathrm{t}$ $5.007356665(62) \times 10^{- 27}$ $\mathrm{kg}$ $1.2 \times 10^{- 8}$ Triton mass

$m_\mathrm{t}$ $3.01550071632(11)$ $\mathrm{u}$ $3.6 \times 10^{- 11}$ Triton mass

$m_\mathrm{t} c^2$ $4.500387735(55) \times 10^{- 10}$ $\mathrm{J}$ $1.2 \times 10^{- 8}$ Triton mass, energy equivalent

$m_\mathrm{t} c^2$ $2808.921112(17)$ $\mathrm{M eV}$ $6.2 \times 10^{- 9}$ Triton mass, energy equivalent

$\dfrac{m_\mathrm{t}}{m_\mathrm{e}}$ $5496.92153588(26)$ $4.6 \times 10^{- 11}$ Triton-electron mass ratio

$\dfrac{m_\mathrm{t}}{m_\mathrm{p}}$ $2.99371703348(22)$ $7.5 \times 10^{- 11}$ Triton-proton mass ratio

$M (t), M_\mathrm{t}$ $3.01550071632(11) \times 10^{- 3}$ $\mathrm{kg \cdot mol^{- 1}}$ $3.6 \times 10^{- 11}$ Triton molar mass $N_\mathrm{A} m_\mathrm{t}$

$\mu_\mathrm{t}$ $1.504609503(12) \times 10^{- 26}$ $\mathrm{J \cdot T^{- 1}}$ $7.8 \times 10^{- 9}$ Triton magnetic moment

$\dfrac{\mu_\mathrm{t}}{\mu_\mathrm{B}}$ $1.6223936616(76) \times 10^{- 3}$ $4.7 \times 10^{- 9}$ Triton magnetic moment, to Bohr magneton ratio

$\dfrac{\mu_\mathrm{t}}{\mu_\mathrm{N}}$ $2.978962460(14)$ $4.7 \times 10^{- 9}$ Triton magnetic moment, to Bohr magneton ratio

$g_\mathrm{t}$ $5.957924920(28)$ $4.7 \times 10^{- 9}$ Triton g-factor $\dfrac{2 \mu_\mathrm{t}}{\mu_\mathrm{N}}$

Symbol	Numerical Value	Unit	Relative Standard Uncertainty	`Quantity`
$m_\mathrm{t}$	$5.007356665(62) \times 10^{- 27}$	$\mathrm{kg}$	$1.2 \times 10^{- 8}$	Triton mass
$m_\mathrm{t}$	$3.01550071632(11)$	$\mathrm{u}$	$3.6 \times 10^{- 11}$	Triton mass
$m_\mathrm{t} c^2$	$4.500387735(55) \times 10^{- 10}$	$\mathrm{J}$	$1.2 \times 10^{- 8}$	Triton mass, energy equivalent
$m_\mathrm{t} c^2$	$2808.921112(17)$	$\mathrm{M eV}$	$6.2 \times 10^{- 9}$	Triton mass, energy equivalent
$\dfrac{m_\mathrm{t}}{m_\mathrm{e}}$	$5496.92153588(26)$		$4.6 \times 10^{- 11}$	Triton-electron mass ratio
$\dfrac{m_\mathrm{t}}{m_\mathrm{p}}$	$2.99371703348(22)$		$7.5 \times 10^{- 11}$	Triton-proton mass ratio
$M (t), M_\mathrm{t}$	$3.01550071632(11) \times 10^{- 3}$	$\mathrm{kg \cdot mol^{- 1}}$	$3.6 \times 10^{- 11}$	Triton molar mass $N_\mathrm{A} m_\mathrm{t}$
$\mu_\mathrm{t}$	$1.504609503(12) \times 10^{- 26}$	$\mathrm{J \cdot T^{- 1}}$	$7.8 \times 10^{- 9}$	Triton magnetic moment
$\dfrac{\mu_\mathrm{t}}{\mu_\mathrm{B}}$	$1.6223936616(76) \times 10^{- 3}$		$4.7 \times 10^{- 9}$	Triton magnetic moment, to Bohr magneton ratio
$\dfrac{\mu_\mathrm{t}}{\mu_\mathrm{N}}$	$2.978962460(14)$		$4.7 \times 10^{- 9}$	Triton magnetic moment, to Bohr magneton ratio
$g_\mathrm{t}$	$5.957924920(28)$		$4.7 \times 10^{- 9}$	Triton g-factor $\dfrac{2 \mu_\mathrm{t}}{\mu_\mathrm{N}}$

Helion, $\mathrm{h}$

Symbol Numerical Value Unit Relative Standard Uncertainty Quantity

$m_\mathrm{h}$ $5.006412700(62) \times 10^{- 27}$ $\mathrm{kg}$ $1.2 \times 10^{- 8}$ Helion mass

$m_\mathrm{h}$ $3.01493224673(12)$ $\mathrm{u}$ $3.9 \times 10^{- 11}$ Helion mass

$m_\mathrm{h} c^2$ $4.499539341(55) \times 10^{- 10}$ $\mathrm{J}$ $1.2 \times 10^{- 8}$ Helion mass, energy equivalent

$m_\mathrm{h} c^2$ $2808.391586(17)$ $\mathrm{M eV}$ $6.2 \times 10^{- 9}$ Helion mass, energy equivalent

$\dfrac{m_\mathrm{h}}{m_\mathrm{e}}$ $5495.88527922(27)$ $4.9 \times 10^{- 11}$ Helion-electron mass ratio

$\dfrac{m_\mathrm{h}}{m_\mathrm{p}}$ $2.99315267046(29)$ $9.6 \times 10^{- 11}$ Helion-proton mass ratio

$M (h), M_\mathrm{h}$ $3.01493224673(12) \times 10^{- 3}$ $\mathrm{kg \cdot mol^{- 1}}$ $3.9 \times 10^{- 11}$ Helion molar mass $N_\mathrm{A} m_\mathrm{h}$

$\mu_\mathrm{h}$ $- 1.074617522(14) \times 10^{- 26}$ $\mathrm{J \cdot T^{- 1}}$ $1.3 \times 10^{- 8}$ Helion magnetic moment

$\dfrac{\mu_\mathrm{h}}{\mu_\mathrm{B}}$ $- 1.158740958(14) \times 10^{ -3}$ $1.2 \times 10^{- 8}$ Helion magnetic moment, to Bohr magneton ratio

$\dfrac{\mu_\mathrm{h}}{\mu_\mathrm{N}}$ $- 2.127625308(25)$ $1.2 \times 10^{- 8}$ Helion magnetic moment, to nuclear magneton ratio

$g_\mathrm{h}$ $- 4.255250616(50)$ $1.2 \times 10^{- 8}$ Helion g-factor $\dfrac{2 \mu_\mathrm{h}}{\mu_\mathrm{N}}$

$\mu_\mathrm{h}’$ $- 1.074553080(14) \times 10^{- 26}$ $\mathrm{J \cdot T^{- 1}}$ $1.3 \times 10^{- 8}$ Shielded helion magnetic moment (gas, sphere, $\mathrm{25 ^\circ C}$)

$\dfrac{\mu_\mathrm{h}’}{\mu_\mathrm{B}}$ $- 1.158671471(14) \times 10^{- 3}$ $1.2 \times 10^{- 8}$ Shielded helion magnetic moment (gas, sphere, $\mathrm{25 ^\circ C}$), to Bohr magneton ratio

$\dfrac{\mu_\mathrm{h}}{\mu_\mathrm{N}}$ $- 2.127497720(25)$ $1.2 \times 10^{- 8}$ Shielded helion magnetic moment (gas, sphere, $\mathrm{25 ^\circ C}$), to nuclear magneton ratio

$\dfrac{\mu_\mathrm{h}}{\mu_\mathrm{p}}$ $- 0.7617665603(92)$ $1.2 \times 10^{- 8}$ Shielded helion to proton magneticmoment (gas, sphere, $\mathrm{25 ^\circ C}$)

$\dfrac{\mu_\mathrm{h}’}{\mu_\mathrm{p}’}$ $- 0.7617861313(33)$ $4.3 \times 10^{- 9}$ Shielded helion to shielded proton (gas/$\ce{H_2 O}$, spheres, $\mathrm{25 ^\circ C}$)

$\gamma_\mathrm{h}’$ $2.037894585(27) \times 10^8$ $\mathrm{s^{- 1} \cdot T^{- 1}}$ $1.3 \times 10^{- 8}$ Shielded helion gyromagnetic ratio $\dfrac{2 \lvert \mu_\mathrm{h}’ \rvert}{\hbar}$ (gas, sphere, $\mathrm{25 ^\circ C}$)

$\dfrac{\gamma_\mathrm{h}’}{2 \pi}$ $32.43409966(43)$ $\mathrm{M Hz \cdot T^{- 1}}$ $1.3 \times 10^{- 8}$ Shielded helion gyromagnetic ratio $\dfrac{2 \lvert \mu_\mathrm{h}’ \rvert}{\hbar}$ (gas, sphere, $\mathrm{25 ^\circ C}$)

Symbol	Numerical Value	Unit	Relative Standard Uncertainty	`Quantity`
$m_\mathrm{h}$	$5.006412700(62) \times 10^{- 27}$	$\mathrm{kg}$	$1.2 \times 10^{- 8}$	Helion mass
$m_\mathrm{h}$	$3.01493224673(12)$	$\mathrm{u}$	$3.9 \times 10^{- 11}$	Helion mass
$m_\mathrm{h} c^2$	$4.499539341(55) \times 10^{- 10}$	$\mathrm{J}$	$1.2 \times 10^{- 8}$	Helion mass, energy equivalent
$m_\mathrm{h} c^2$	$2808.391586(17)$	$\mathrm{M eV}$	$6.2 \times 10^{- 9}$	Helion mass, energy equivalent
$\dfrac{m_\mathrm{h}}{m_\mathrm{e}}$	$5495.88527922(27)$		$4.9 \times 10^{- 11}$	Helion-electron mass ratio
$\dfrac{m_\mathrm{h}}{m_\mathrm{p}}$	$2.99315267046(29)$		$9.6 \times 10^{- 11}$	Helion-proton mass ratio
$M (h), M_\mathrm{h}$	$3.01493224673(12) \times 10^{- 3}$	$\mathrm{kg \cdot mol^{- 1}}$	$3.9 \times 10^{- 11}$	Helion molar mass $N_\mathrm{A} m_\mathrm{h}$
$\mu_\mathrm{h}$	$- 1.074617522(14) \times 10^{- 26}$	$\mathrm{J \cdot T^{- 1}}$	$1.3 \times 10^{- 8}$	Helion magnetic moment
$\dfrac{\mu_\mathrm{h}}{\mu_\mathrm{B}}$	$- 1.158740958(14) \times 10^{ -3}$		$1.2 \times 10^{- 8}$	Helion magnetic moment, to Bohr magneton ratio
$\dfrac{\mu_\mathrm{h}}{\mu_\mathrm{N}}$	$- 2.127625308(25)$		$1.2 \times 10^{- 8}$	Helion magnetic moment, to nuclear magneton ratio
$g_\mathrm{h}$	$- 4.255250616(50)$		$1.2 \times 10^{- 8}$	Helion g-factor $\dfrac{2 \mu_\mathrm{h}}{\mu_\mathrm{N}}$
$\mu_\mathrm{h}’$	$- 1.074553080(14) \times 10^{- 26}$	$\mathrm{J \cdot T^{- 1}}$	$1.3 \times 10^{- 8}$	Shielded helion magnetic moment (gas, sphere, $\mathrm{25 ^\circ C}$)
$\dfrac{\mu_\mathrm{h}’}{\mu_\mathrm{B}}$	$- 1.158671471(14) \times 10^{- 3}$		$1.2 \times 10^{- 8}$	Shielded helion magnetic moment (gas, sphere, $\mathrm{25 ^\circ C}$), to Bohr magneton ratio
$\dfrac{\mu_\mathrm{h}}{\mu_\mathrm{N}}$	$- 2.127497720(25)$		$1.2 \times 10^{- 8}$	Shielded helion magnetic moment (gas, sphere, $\mathrm{25 ^\circ C}$), to nuclear magneton ratio
$\dfrac{\mu_\mathrm{h}}{\mu_\mathrm{p}}$	$- 0.7617665603(92)$		$1.2 \times 10^{- 8}$	Shielded helion to proton magneticmoment (gas, sphere, $\mathrm{25 ^\circ C}$)
$\dfrac{\mu_\mathrm{h}’}{\mu_\mathrm{p}’}$	$- 0.7617861313(33)$		$4.3 \times 10^{- 9}$	Shielded helion to shielded proton (gas/$\ce{H_2 O}$, spheres, $\mathrm{25 ^\circ C}$)
$\gamma_\mathrm{h}’$	$2.037894585(27) \times 10^8$	$\mathrm{s^{- 1} \cdot T^{- 1}}$	$1.3 \times 10^{- 8}$	Shielded helion gyromagnetic ratio $\dfrac{2 \lvert \mu_\mathrm{h}’ \rvert}{\hbar}$ (gas, sphere, $\mathrm{25 ^\circ C}$)
$\dfrac{\gamma_\mathrm{h}’}{2 \pi}$	$32.43409966(43)$	$\mathrm{M Hz \cdot T^{- 1}}$	$1.3 \times 10^{- 8}$	Shielded helion gyromagnetic ratio $\dfrac{2 \lvert \mu_\mathrm{h}’ \rvert}{\hbar}$ (gas, sphere, $\mathrm{25 ^\circ C}$)

Alpha particle, $\alpha$

Symbol Numerical Value Unit Relative Standard Uncertainty Quantity

$m_\alpha$ $6.644657230(82) \times 10^{- 27}$ $\mathrm{kg}$ $1.2 \times 10^{- 8}$ Alpha particle mass

$m_\alpha$ $4.001506179127(63)$ $\mathrm{u}$ $1.6 \times 10^{- 11}$ Alpha particle mass

$m_\alpha c^2$ $5.971920097(73) \times 10^{- 10}$ $\mathrm{J}$ $1.2 \times 10^{- 8}$ Alpha particle mass, energy equivalent

$m_\alpha c^2$ $3727.379378(23)$ $\mathrm{M eV}$ $6.2 \times 10^{- 9}$ Alpha particle mass, energy equivalent

$\dfrac{m_\alpha}{m_\mathrm{e}}$ $7294.29954136(24)$ $3.3 \times 10^{- 11}$ Alpha particle to electron mass ratio

$\dfrac{m_\alpha}{m_\mathrm{p}}$ $3.97259968907(36)$ $9.2 \times 10^{- 11}$ Alpha particle to proton mass ratio

$M (\alpha), M_\alpha$ $4.001506179127(63) \times 10^{- 3}$ $\mathrm{kg \cdot mol^{- 1}}$ $1.6 \times 10^{- 11}$ Alpha particle molar mass $N_\mathrm{A} m_\alpha$

Symbol	Numerical Value	Unit	Relative Standard Uncertainty	`Quantity`
$m_\alpha$	$6.644657230(82) \times 10^{- 27}$	$\mathrm{kg}$	$1.2 \times 10^{- 8}$	Alpha particle mass
$m_\alpha$	$4.001506179127(63)$	$\mathrm{u}$	$1.6 \times 10^{- 11}$	Alpha particle mass
$m_\alpha c^2$	$5.971920097(73) \times 10^{- 10}$	$\mathrm{J}$	$1.2 \times 10^{- 8}$	Alpha particle mass, energy equivalent
$m_\alpha c^2$	$3727.379378(23)$	$\mathrm{M eV}$	$6.2 \times 10^{- 9}$	Alpha particle mass, energy equivalent
$\dfrac{m_\alpha}{m_\mathrm{e}}$	$7294.29954136(24)$		$3.3 \times 10^{- 11}$	Alpha particle to electron mass ratio
$\dfrac{m_\alpha}{m_\mathrm{p}}$	$3.97259968907(36)$		$9.2 \times 10^{- 11}$	Alpha particle to proton mass ratio
$M (\alpha), M_\alpha$	$4.001506179127(63) \times 10^{- 3}$	$\mathrm{kg \cdot mol^{- 1}}$	$1.6 \times 10^{- 11}$	Alpha particle molar mass $N_\mathrm{A} m_\alpha$

Physicochemical

Symbol Numerical Value Unit Relative Standard Uncertainty Quantity

$N_\mathrm{A}, L$ $6.022140857(74) \times 10^{23}$ $\mathrm{mol^{- 1}}$ $1.2 \times 10^{- 8}$ Avogadro constant

$m_\mathrm{u}$ $1.660539040(20) \times 10^{- 27}$ $\mathrm{kg}$ $1.2 \times 10^{- 8}$ Atomic mass constant $m_\mathrm{u} = \dfrac{1}{12} m (\ce{^{12} C}) = 1 \mathrm{u}$

$m_\mathrm{u} c^2$ $1.492418062(18) \times 10^{- 10}$ $\mathrm{J}$ $1.2 \times 10^{- 8}$ Atomic mass constant $m_\mathrm{u} = \dfrac{1}{12} m (\ce{^{12} C}) = 1 \mathrm{u}$, energy equivalent

$m_\mathrm{u} c^2$ $931.4940954(57)$ $\mathrm{M eV}$ $6.2 \times 10^{- 9}$ Atomic mass constant $m_\mathrm{u} = \dfrac{1}{12} m (\ce{^{12} C}) = 1 \mathrm{u}$, energy equivalent

$F$ $96485.33289(59)$ $\mathrm{C \cdot mol^{- 1}}$ $6.2 \times 10^{- 9}$ Faraday constant $N_\mathrm{A} e$

$N_\mathrm{A} h$ $3.9903127110(18) \times 10^{- 10}$ $\mathrm{J \cdot s \cdot mol^{- 1}}$ $4.5 \times 10^{- 10}$ Molar Planck constant

$N_\mathrm{A} h c$ $0.119626565582(54)$ $\mathrm{J \cdot m \cdot mol^{- 1}}$ $4.5 \times 10^{- 10}$ Molar Planck constant

$R$ $8.3144598(48)$ $\mathrm{J \cdot mol^{- 1} \cdot K^{- 1}}$ $5.7 \times 10^{- 7}$ Molar gas constant

$k$ $1.38064852(79) \times 10^{- 23}$ $\mathrm{J \cdot K^{- 1}}$ $5.7 \times 10^{- 7}$ Boltzmann constant $\dfrac{R}{N_\mathrm{A}}$

$k$ $8.6173303(50) \times 10^{- 5}$ $\mathrm{eV \cdot K^{- 1}}$ $5.7 \times 10^{- 7}$ Boltzmann constant $\dfrac{R}{N_\mathrm{A}}$

$\dfrac{k}{h}$ $2.0836612(12) \times 10^{10}$ $\mathrm{Hz \cdot K^{- 1}}$ $5.7 \times 10^{- 7}$ Boltzmann constant $\dfrac{R}{N_\mathrm{A}}$

$\dfrac{k}{h c}$ $69.503457(40)$ $\mathrm{m^{- 1} \cdot K^{- 1}}$ $5.7 \times 10^{- 7}$ Boltzmann constant $\dfrac{R}{N_\mathrm{A}}$

$V_\mathrm{m}$ $22.710947(13) \times 10^{- 3}$ $\mathrm{m^3 \cdot mol^{- 1}}$ $5.7 \times 10^{- 7}$ Molar volume of ideal gas $\dfrac{R T}{p}$ $T = 273.15 \mathrm{K}, p = 100 \mathrm{k Pa}$

$n_0$ $2.6516467(15) \times 10^{25}$ $\mathrm{m^{- 3}}$ $5.7 \times 10^{- 7}$ Molar volume of ideal gas $\dfrac{R T}{p}$ $T = 273.15 \mathrm{K}, p = 100 \mathrm{k Pa}$, Loschmidt constant $\dfrac{N_\mathrm{A}}{V_\mathrm{m}}$

$V_\mathrm{m}$ $22.413962(13) \times 10^{- 3}$ $\mathrm{m^3 \cdot mol^{- 1}}$ $5.7 \times 10^{- 7}$ Molar volume of ideal gas $\dfrac{R T}{p}$ $T = 273.15 \mathrm{K}, p = 101.325 \mathrm{k Pa}$

$n_0$ $2.6867811(15) \times 10^{25}$ $m^{- 3}$ $5.7 \times 10^{- 7}$ Molar volume of ideal gas $\dfrac{R T}{p}$ $T = 273.15 \mathrm{K}, p = 101.325 \mathrm{k Pa}$, Loschmidt constant $\dfrac{N_\mathrm{A}}{V_\mathrm{m}}$

$\dfrac{S_0}{R}$ $- 1.1517084(14)$ $1.2 \times 10^{- 6}$ Sackur-Tetrode (absolute entropy) constant $\dfrac{5}{2} + \ln \left[ \left( \dfrac{2 \pi m_\mathrm{u} k T_1}{h^2} \right)^\frac{3}{2} \dfrac{k T_1}{p_0} \right]$ $T_1 = 1 \mathrm{K}, p_0 = 100 \mathrm{k Pa}$

$\dfrac{S_0}{R}$ $- 1.1648714(14)$ $1.2 \times 10^{- 6}$ Sackur-Tetrode (absolute entropy) constant $\dfrac{5}{2} + \ln \left[ \left( \dfrac{2 \pi m_\mathrm{u} k T_1}{h^2} \right)^\frac{3}{2} \dfrac{k T_1}{p_0} \right]$ $T_1 = 1 \mathrm{K}, p_0 = 101.325 \mathrm{k Pa}$

$\sigma$ $5.670367(13) \times 10^{- 8}$ $\mathrm{W \cdot m^{- 2} \cdot K^{- 4}}$ $2.3 \times 10^{- 6}$ Stefan-Boltzmann constant $\dfrac{\dfrac{\pi^2}{60} k^4}{\hbar^3 c^2}$

$c_1$ $3.741771790(46) \times 10^{- 16}$ $\mathrm{W \cdot m^2}$ $1.2 \times 10^{- 8}$ First radiation constant $2 \pi h c^2$

$c_\mathrm{1 L}$ $1.191042953(15) \times 10^{- 16}$ $\mathrm{W \cdot m^2 \cdot sr^{- 1}}$ $1.2 \times 10^{- 8}$ First radiation constant for spectral radiance $2 h c^2$

$c_2$ $1.43877736(83) \times 10^{- 2}$ $\mathrm{m \cdot K}$ $5.7 \times 10^{- 7}$ Second radiation constant $\dfrac{h c}{k}$

$b$ $2.8977729(17) \times 10^{-3}$ $\mathrm{m \cdot K}$ $5.7 \times 10^{- 7}$ Wien displacement law constants $b = \lambda_\mathrm{max} T = \dfrac{c_2}{4.965114231 \ldots} $

$b’$ $5.8789238(34) \times 10^{10}$ $\mathrm{Hz \cdot K^{- 1}}$ $5.7 \times 10^{- 7}$ Wien displacement law constants $b’ = \dfrac{\nu_\mathrm{max}}{T} = \dfrac{2.821439372 \ldots c}{c_2}$

Symbol	Numerical Value	Unit	Relative Standard Uncertainty	`Quantity`
$N_\mathrm{A}, L$	$6.022140857(74) \times 10^{23}$	$\mathrm{mol^{- 1}}$	$1.2 \times 10^{- 8}$	Avogadro constant
$m_\mathrm{u}$	$1.660539040(20) \times 10^{- 27}$	$\mathrm{kg}$	$1.2 \times 10^{- 8}$	Atomic mass constant $m_\mathrm{u} = \dfrac{1}{12} m (\ce{^{12} C}) = 1 \mathrm{u}$
$m_\mathrm{u} c^2$	$1.492418062(18) \times 10^{- 10}$	$\mathrm{J}$	$1.2 \times 10^{- 8}$	Atomic mass constant $m_\mathrm{u} = \dfrac{1}{12} m (\ce{^{12} C}) = 1 \mathrm{u}$, energy equivalent
$m_\mathrm{u} c^2$	$931.4940954(57)$	$\mathrm{M eV}$	$6.2 \times 10^{- 9}$	Atomic mass constant $m_\mathrm{u} = \dfrac{1}{12} m (\ce{^{12} C}) = 1 \mathrm{u}$, energy equivalent
$F$	$96485.33289(59)$	$\mathrm{C \cdot mol^{- 1}}$	$6.2 \times 10^{- 9}$	Faraday constant $N_\mathrm{A} e$
$N_\mathrm{A} h$	$3.9903127110(18) \times 10^{- 10}$	$\mathrm{J \cdot s \cdot mol^{- 1}}$	$4.5 \times 10^{- 10}$	Molar Planck constant
$N_\mathrm{A} h c$	$0.119626565582(54)$	$\mathrm{J \cdot m \cdot mol^{- 1}}$	$4.5 \times 10^{- 10}$	Molar Planck constant
$R$	$8.3144598(48)$	$\mathrm{J \cdot mol^{- 1} \cdot K^{- 1}}$	$5.7 \times 10^{- 7}$	Molar gas constant
$k$	$1.38064852(79) \times 10^{- 23}$	$\mathrm{J \cdot K^{- 1}}$	$5.7 \times 10^{- 7}$	Boltzmann constant $\dfrac{R}{N_\mathrm{A}}$
$k$	$8.6173303(50) \times 10^{- 5}$	$\mathrm{eV \cdot K^{- 1}}$	$5.7 \times 10^{- 7}$	Boltzmann constant $\dfrac{R}{N_\mathrm{A}}$
$\dfrac{k}{h}$	$2.0836612(12) \times 10^{10}$	$\mathrm{Hz \cdot K^{- 1}}$	$5.7 \times 10^{- 7}$	Boltzmann constant $\dfrac{R}{N_\mathrm{A}}$
$\dfrac{k}{h c}$	$69.503457(40)$	$\mathrm{m^{- 1} \cdot K^{- 1}}$	$5.7 \times 10^{- 7}$	Boltzmann constant $\dfrac{R}{N_\mathrm{A}}$
$V_\mathrm{m}$	$22.710947(13) \times 10^{- 3}$	$\mathrm{m^3 \cdot mol^{- 1}}$	$5.7 \times 10^{- 7}$	Molar volume of ideal gas $\dfrac{R T}{p}$ $T = 273.15 \mathrm{K}, p = 100 \mathrm{k Pa}$
$n_0$	$2.6516467(15) \times 10^{25}$	$\mathrm{m^{- 3}}$	$5.7 \times 10^{- 7}$	Molar volume of ideal gas $\dfrac{R T}{p}$ $T = 273.15 \mathrm{K}, p = 100 \mathrm{k Pa}$, Loschmidt constant $\dfrac{N_\mathrm{A}}{V_\mathrm{m}}$
$V_\mathrm{m}$	$22.413962(13) \times 10^{- 3}$	$\mathrm{m^3 \cdot mol^{- 1}}$	$5.7 \times 10^{- 7}$	Molar volume of ideal gas $\dfrac{R T}{p}$ $T = 273.15 \mathrm{K}, p = 101.325 \mathrm{k Pa}$
$n_0$	$2.6867811(15) \times 10^{25}$	$m^{- 3}$	$5.7 \times 10^{- 7}$	Molar volume of ideal gas $\dfrac{R T}{p}$ $T = 273.15 \mathrm{K}, p = 101.325 \mathrm{k Pa}$, Loschmidt constant $\dfrac{N_\mathrm{A}}{V_\mathrm{m}}$
$\dfrac{S_0}{R}$	$- 1.1517084(14)$		$1.2 \times 10^{- 6}$	Sackur-Tetrode (absolute entropy) constant $\dfrac{5}{2} + \ln \left[ \left( \dfrac{2 \pi m_\mathrm{u} k T_1}{h^2} \right)^\frac{3}{2} \dfrac{k T_1}{p_0} \right]$ $T_1 = 1 \mathrm{K}, p_0 = 100 \mathrm{k Pa}$
$\dfrac{S_0}{R}$	$- 1.1648714(14)$		$1.2 \times 10^{- 6}$	Sackur-Tetrode (absolute entropy) constant $\dfrac{5}{2} + \ln \left[ \left( \dfrac{2 \pi m_\mathrm{u} k T_1}{h^2} \right)^\frac{3}{2} \dfrac{k T_1}{p_0} \right]$ $T_1 = 1 \mathrm{K}, p_0 = 101.325 \mathrm{k Pa}$
$\sigma$	$5.670367(13) \times 10^{- 8}$	$\mathrm{W \cdot m^{- 2} \cdot K^{- 4}}$	$2.3 \times 10^{- 6}$	Stefan-Boltzmann constant $\dfrac{\dfrac{\pi^2}{60} k^4}{\hbar^3 c^2}$
$c_1$	$3.741771790(46) \times 10^{- 16}$	$\mathrm{W \cdot m^2}$	$1.2 \times 10^{- 8}$	First radiation constant $2 \pi h c^2$
$c_\mathrm{1 L}$	$1.191042953(15) \times 10^{- 16}$	$\mathrm{W \cdot m^2 \cdot sr^{- 1}}$	$1.2 \times 10^{- 8}$	First radiation constant for spectral radiance $2 h c^2$
$c_2$	$1.43877736(83) \times 10^{- 2}$	$\mathrm{m \cdot K}$	$5.7 \times 10^{- 7}$	Second radiation constant $\dfrac{h c}{k}$
$b$	$2.8977729(17) \times 10^{-3}$	$\mathrm{m \cdot K}$	$5.7 \times 10^{- 7}$	Wien displacement law constants $b = \lambda_\mathrm{max} T = \dfrac{c_2}{4.965114231 \ldots} $
$b’$	$5.8789238(34) \times 10^{10}$	$\mathrm{Hz \cdot K^{- 1}}$	$5.7 \times 10^{- 7}$	Wien displacement law constants $b’ = \dfrac{\nu_\mathrm{max}}{T} = \dfrac{2.821439372 \ldots c}{c_2}$