# Commonly Used Physical Constants

Uncertainty should be read as 1.234(56) = 1.234${\displaystyle \pm }$0.056
Name Symbol Value Units Relative Uncertainty
Speed of light (in vacuum) ${\displaystyle c}$ ${\displaystyle 299\ 792\ 458}$ ${\displaystyle \mathrm {m} \ \mathrm {s} ^{-1}}$ (exact)
Magnetic Constant ${\displaystyle \mu _{0}}$ ${\displaystyle 4\pi \times 10^{-7}\approx 12.566\ 370\ 6\times 10^{-7}}$ ${\displaystyle \mathrm {N} \ \mathrm {A} ^{-2}}$ (exact)
Electric Constant ${\displaystyle \varepsilon _{0}=1/\left(\mu _{0}c^{2}\right)}$ ${\displaystyle \approx 8.854\ 187\ 817\times 10^{-12}}$ ${\displaystyle \mathrm {F} \ \mathrm {m} ^{-1}}$ (exact)
Newtonian Gravitaional Constant ${\displaystyle G}$ ${\displaystyle 6.674\ 2(10)\times 10^{-11}}$ ${\displaystyle \mathrm {m} ^{3}\ \mathrm {kg} ^{-1}\ \mathrm {s} ^{-2}}$ ${\displaystyle 1.5\times 10^{-4}}$
Plank's Constant ${\displaystyle h}$ ${\displaystyle 6.626\ 069\ 3(11)\times 10^{-34}}$ ${\displaystyle \mathrm {J} \ \mathrm {s} }$ ${\displaystyle 1.7\times 10^{-7}}$
Elementary charge ${\displaystyle e}$ ${\displaystyle 1.602\ 176\ 53(14)\times 10^{-19}}$ ${\displaystyle \mathrm {C} }$ ${\displaystyle 8.5\times 10^{-8}}$
Mass of the electron ${\displaystyle m_{e}}$ ${\displaystyle 9.109\ 382\ 6(16)\times 10^{-31}}$ ${\displaystyle \mathrm {kg} }$ ${\displaystyle 1.7\times 10^{-7}}$
Mass of the proton ${\displaystyle m_{p}}$ ${\displaystyle 1.672\ 621\ 71(29)\times 10^{-27}}$ ${\displaystyle \mathrm {kg} }$ ${\displaystyle 1.7\times 10^{-7}}$
Fine structure constant ${\displaystyle \alpha ={\frac {e^{2}}{4\pi \varepsilon _{0}\hbar c}}}$ ${\displaystyle 7.297\ 352\ 568(24)\times 10^{-3}}$ dimensionless ${\displaystyle 3.3\times 10^{-9}}$
Molar gass constant ${\displaystyle R}$ ${\displaystyle 8.314\ 472(15)}$ ${\displaystyle \mathrm {J} \ \mathrm {mol} ^{-1}\ \mathrm {K} ^{-1}}$ ${\displaystyle 1.7\times 10^{-6}}$
Boltzmann's constant ${\displaystyle k}$ ${\displaystyle 1.380\ 650\ 5(24)\times 10^{-23}}$ ${\displaystyle \mathrm {J} \ \mathrm {K} ^{-1}}$ ${\displaystyle 1.8\times 10^{-6}}$
Avogadro's Number ${\displaystyle N_{\text{A}},L}$ ${\displaystyle 6.022\ 141\ 5(10)\times 10^{23}}$ ${\displaystyle \mathrm {mol} ^{-1}}$ ${\displaystyle 1.7\times 10^{-7}}$
Rydberg constant ${\displaystyle R_{\infty }}$ ${\displaystyle 10\ 973\ 731.568\ 525(73)}$ ${\displaystyle \mathrm {m} ^{-1}}$ ${\displaystyle 6.6\times 10^{-12}}$
Standard acceleration of gravity ${\displaystyle g}$ ${\displaystyle 9.806\ 65}$ ${\displaystyle \mathrm {m} \ \mathrm {s} ^{-2}}$ defined
Atmospheric pressure ${\displaystyle \mathrm {atm} }$ ${\displaystyle 101\ 325}$ ${\displaystyle \mathrm {Pa} }$ defined
Bohr Radius ${\displaystyle a_{0}\ }$ ${\displaystyle 0.529\ 177\ 208\ 59(36)\times 10^{-10}\ }$ ${\displaystyle \mathrm {m} \ }$ ${\displaystyle 6.8\times 10^{-10}}$
Electron Volt ${\displaystyle eV}$ ${\displaystyle 1.602\ 176\ 53(14)\times 10^{-19}}$ ${\displaystyle \mathrm {J} }$ ${\displaystyle 8.7\times 10^{-8}}$
Luminous efficacy of monochromatic radiation ${\displaystyle K_{cd}}$ ${\displaystyle 683}$ ${\displaystyle \mathrm {lm/W} }$ (exact)
hyperfine transition frequency of Cs-133 ${\displaystyle \Delta \nu _{\text{Cs}}}$ ${\displaystyle 9\ 192\ 631\ 770}$ ${\displaystyle \mathrm {Hz} }$ (exact)
Reduced Planck constant ${\displaystyle \hbar =h/2\pi }$ ${\displaystyle 1.054\ 571\ 817\times {10}^{-34}}$ ${\displaystyle \mathrm {J} \cdot \mathrm {s} }$ (exact)
atomic mass of Carbon 12 ${\displaystyle m({}^{12}{\text{C}})}$ ${\displaystyle 1.992\ 646\ 879\ 92(60)\times {10}^{-26}}$ ${\displaystyle \mathrm {kg} }$
molar mass of Carbon-12 ${\displaystyle M({}^{12}{\text{C}})=N_{\text{A}}m({}^{12}{\text{C}})}$ ${\displaystyle 11.999\ 999\ 9958(36)\times {10}^{-3}}$ ${\displaystyle \mathrm {kg\cdot {mol}^{-1}} }$
atomic mass constant ${\displaystyle m_{\text{u}}=m({}^{12}{\text{C}})/12=1\,{\text{Da}}}$ ${\displaystyle 1.660\ 539\ 066\ 60(50)\times {10}^{-27}}$ ${\displaystyle \mathrm {kg} }$
molar mass constant ${\displaystyle M_{\text{u}}=M({}^{12}{\text{C}})/12=N_{\text{A}}m_{\text{u}}}$ ${\displaystyle 0.999\ 999\ 999\ 65(30)\times {10}^{-3}}$ ${\displaystyle \mathrm {kg\cdot {mol}^{-1}} }$
molar volume of silicon ${\displaystyle V_{m}(\mathrm {Si} )}$ ${\displaystyle 1.205\ 883\ 199(60)\times {10}^{-5}}$ ${\displaystyle \mathrm {m^{3}\cdot {mol}^{-1}} }$
molar Planck constant ${\displaystyle N_{\text{A}}h}$ ${\displaystyle 3.990\ 312\ 712\ldots {10}^{-10}}$ ${\displaystyle \mathrm {J\cdot {Hz}^{-1}\cdot {mol}^{-1}} }$
Stefan-Boltzmann constant ${\displaystyle \sigma =\pi ^{2}k_{B}^{4}/60\hbar ^{3}c^{2}}$ ${\displaystyle 5.670\ 374\ 419\ldots \times {10}^{-8}}$ ${\displaystyle \mathrm {W\cdot m^{-2}\cdot K^{-4}} }$
first radiation constant ${\displaystyle c_{1}=2\pi hc^{2}}$ ${\displaystyle 3.741\ 771\ 852\ldots {10}^{-16}}$ ${\displaystyle \mathrm {W\cdot m^{2}} }$
first radiation constant for spectral radiance ${\displaystyle c_{\text{1L}}=2hc^{2}/sr}$[1] ${\displaystyle 1.191\ 042\ 972\ 397\ 188\ 414\ 079\ 4892\times {10}^{-16}}$ ${\displaystyle \mathrm {W\cdot m^{2}{sr}^{-1}} }$
second radiation constant ${\displaystyle c_{2}=hc/k_{B}}$ ${\displaystyle 1.438\ 776\ 877\ldots \times {10}^{-2}}$ ${\displaystyle \mathrm {m\cdot K} }$
Wien wavelength displacement constant ${\displaystyle b}$ ${\displaystyle 2.897\ 771\ 955\ldots \times {10}^{-3}}$ ${\displaystyle \mathrm {m\cdot K} }$
Wien frequency displacement constant ${\displaystyle b'=c/b}$ ${\displaystyle 5.878\ 925\ 757\ \times {10}^{10}}$ ${\displaystyle \mathrm {Hz\cdot K^{-1}} }$
Wien entropy displacement constant ${\displaystyle b_{\text{entropy}}}$ ${\displaystyle 3.002\ 916\ 077\ldots \times {10}^{-3}}$ ${\displaystyle \mathrm {m\cdot K} }$
Faraday constant ${\displaystyle F=N_{\text{A}}e}$[2] ${\displaystyle 96\ 485.332\ 123\ 310\ 0184}$ ${\displaystyle \mathrm {C\cdot {mol}^{-1}} }$

## To Be Merged Into Table

This list is prepared in the format

• Constant (symbol) : value

• Coulomb's Law Constant (k) : 1/(4 π ε0) = 9.0 × 109 N·m2/C2
• Faraday constant (F)  : 96,485 C·mol−1
• Mass of a neutron (mn) : 1.67495 × 10−27 kg
• Mass of Earth : 5.98 × 1024 kg
• Mass of the Moon : 7.35 × 1022 kg
• Mean radius of Earth : 6.37 × 106 m
• Mean radius of the Moon : 1.74 × 106 m
• Dirac's Constant (${\displaystyle \hbar }$) : ${\displaystyle h/(2\pi )}$ = 1.05457148 × 10−34 J·s
• Speed of sound in air at STP : 3.31 × 102 m/s
• Unified Atomic Mass Unit (u) : 1.66 × 10−27 kg
 Item Proton Neutron Electron Mass 1 1 Negligible Charge +1 0 -1