Fundamental Physical Constants and Unit Conversion Table

Fundamental Physical Constants

Pi (Pi)
100 Digits / 1,000 Digits / 10,000 Digits / 100,000 Digits / 1,000,000 Digits
Pi to 1 Billion (1,000,000,000) Digits [ZIP, 447 MB] 		π\pi == 3.14159265358979323846...3.14159265358979323846...
Avogadro constant (Avogadro constant) NAN_A == 6.02214×1023  mol−16.02214 \times 10^{23} \; mol^{-1}
Boltzmann constant (Boltzmann constant) kBk_B == 1.38065×10−23  JK−11.38065 \times 10^{-23} \; JK^{-1}
Planck constant (Planck constant) hh
ℏ=h/2π\hbar = h/2\pi 		==
== 		6.62607×10−34  Js6.62607 \times 10^{-34} \; Js
1.05457×10−34  Js1.05457 \times 10^{-34} \; Js
Gas constant (gas constant) R=NA kBR = N_A \, k_B == 8.31447  JK−1mol−18.31447 \; JK^{-1}mol^{-1}
Speed of light (speed of light) cc == 2.99792458×108  ms−12.99792458 \times 10^{8} \; ms^{-1}
Elementary charge (elementary charge) ee == 1.60218×10−19  C1.60218 \times 10^{-19} \; C
Faraday constant (Faraday constant) F=NA eF = N_A \, e == 9.6485×104  C mol−19.6485 \times 10^4 \; C\, mol^{-1}
Atomic mass unit (atomic mass unit) mu=1 amum_u = 1 \, amu == 1.66054×10−27  kg1.66054 \times 10^{-27} \; kg
Bohr radius (Bohr radius) a0=1 bohr=4πε0ℏ2/e2mea_0 = 1 \, bohr = 4\pi\varepsilon_0\hbar^2/e^2m_e == 5.29177×10−11  m5.29177 \times 10^{-11} \; m
Electron mass (electron mass) mem_e == 9.10938×10−31  kg9.10938 \times 10^{-31} \; kg
Proton mass (proton mass) mpm_p == 1.67262×10−27  kg1.67262 \times 10^{-27} \; kg
Neutron mass (neutron mass) mnm_n == 1.67493×10−27  kg1.67493 \times 10^{-27} \; kg
Vacuum permittivity (vacuum permittivity) ε0=1/μ0c2\varepsilon_0 = 1/\mu_0c^2
4πε04\pi\varepsilon_0 		==
== 		8.85419×10−12  J−1C2m−18.85419 \times 10^{-12} \; J^{-1}C^2m^{-1}
1.11265×10−10  J−1C2m−11.11265 \times 10^{-10} \; J^{-1}C^2m^{-1}
Vacuum permeability (vacuum permeability) μ0\mu_0 == 4π×10−7  Js2C−2m−14\pi \times 10^{-7} \; Js^2C^{-2}m^{-1}
Bohr magneton (Bohr magneton) μB=eℏ/2me\mu_B = e\hbar/2m_e == 9.27401×10−24  JT−19.27401 \times 10^{-24} \; JT^{-1}
Nuclear magneton (nuclear magneton) μN=eℏ/2mp\mu_N = e\hbar/2m_p == 5.05078×10−27  JT−15.05078 \times 10^{-27} \; JT^{-1}
Free-electron g-factor (electron g-factor) geg_e == 2.002322.00232
Fine-structure constant (fine-structure constant) α=μ0e2c/2h\alpha = \mu_0e^2c/2h
α−1\alpha^{-1} 		==
== 		7.29735×10−37.29735 \times 10^{-3}
1.37036×1021.37036 \times 10^2
Second radiation constant (second radiation constant) c2=hc/kc_2 = hc/k == 1.43878×10−2  mK1.43878 \times 10^{-2} \; mK
Stefan-Boltzmann constant (Stefan-Boltzmann constant) σ=2π5k4/15h3c2\sigma = 2\pi^5k^4/15h^3c^2 == 5.67040×10−8  Wm−2K−45.67040 \times 10^{-8} \; Wm^{-2}K^{-4}
Rydberg constant (Rydberg constant) R∞=mee4/8h3cε02R_{\infty} = m_ee^4/8h^3c{\varepsilon_0}^2 == 1.09737×105  cm−11.09737 \times 10^{5} \; cm^{-1}
Standard gravitational acceleration (standard gravitational acceleration) gg == 9.80665  ms−29.80665 \; ms^{-2}
Gravitational constant (gravitational constant) GG == 6.67428×10−11  Nm2kg−26.67428 \times 10^{-11} \; Nm^2kg^{-2}
(Last Update: January, 2019)

Energy Unit Conversion Table

 hartree (a.u.)hartree \, (a.u.)kJ mol−1kJ \, mol^{-1}kcal mol−1kcal \, mol^{-1}eVeVnmnmcm−1cm^{-1}
1 hartree (a.u.)1 \, hartree \, (a.u.)==112625.52625.5627.51627.5127.21227.21245.56345.5632.1947×1052.1947 \times 10^5
1 kJ mol−11 \, kJ \, mol^{-1}==3.8088×10−43.8088 \times 10^{-4}110.239010.239011.0364×10−21.0364 \times 10^{-2}1.1962×1051.1962 \times 10^{5}83.59383.593
1 kcal mol−11 \, kcal \, mol^{-1}==1.5936×10−31.5936 \times 10^{-3}4.18404.1840114.3363×10−24.3363 \times 10^{-2}2.8591×1042.8591 \times 10^{4}349.75349.75
1 eV1 \, eV==3.6749×10−23.6749 \times 10^{-2}96.48596.48523.06123.061111.2398×1031.2398 \times 10^{3}8065.58065.5
1 nm1 \, nm==45.56345.5631.1962×1051.1962 \times 10^{5}2.8591×1042.8591 \times 10^{4}1.2398×1031.2398 \times 10^{3}111.0000×1071.0000 \times 10^{7}
1 cm−11 \, cm^{-1}==4.5563×10−64.5563 \times 10^{-6}1.1963×10−21.1963 \times 10^{-2}2.8591×10−32.8591 \times 10^{-3}1.2398×10−41.2398 \times 10^{-4}1.0000×1071.0000 \times 10^{7}11