Physical Constants | PhysRef

Speed of Light in Vacuum

Universal

c

299,792,458

m/s

Gravitational Constant

Universal

G

6.674 × 10⁻¹¹

N·m²/kg²

Uncertainty: +/- 0.00015 × 10⁻¹¹ N·m²/kg²

Planck Constant

Universal

h

6.626 × 10⁻³⁴

J·s

Reduced Planck Constant

Universal

ℏ

1.055 × 10⁻³⁴

J·s

Elementary Charge

Electromagnetic

e

1.602 × 10⁻¹⁹

C

Coulomb Constant

Electromagnetic

k

8.988 × 10⁹

N·m²/C²

Vacuum Permittivity

Electromagnetic

ε₀

8.854 × 10⁻¹²

F/m

Vacuum Permeability

Electromagnetic

μ₀

1.257 × 10⁻⁶

H/m

Electron Mass

Atomic

mₑ

9.109 × 10⁻³¹

kg

Proton Mass

Atomic

mₚ

1.673 × 10⁻²⁷

kg

Neutron Mass

Atomic

mₙ

1.675 × 10⁻²⁷

kg

Atomic Mass Unit

Atomic

u

1.661 × 10⁻²⁷

kg

Bohr Radius

Atomic

a₀

5.292 × 10⁻¹¹

m

Rydberg Constant

Atomic

R∞

1.097 × 10⁷

m⁻¹

Boltzmann Constant

Thermodynamic

kB

1.381 × 10⁻²³

J/K

Molar Gas Constant

Thermodynamic

R

8.314

J/(mol·K)

Avogadro Constant

Thermodynamic

Nₐ

6.022 × 10²³

mol⁻¹

Stefan-Boltzmann Constant

Thermodynamic

σ

5.670 × 10⁻⁸

W/(m²·K⁴)

Standard Gravity

Earth

g

9.80665

m/s²

Earth Mass

Earth

M⊕

5.972 × 10²⁴

kg

Earth Radius (mean)

Earth

R⊕

6.371 × 10⁶

m

Solar Mass

Earth

M☉

1.989 × 10³⁰

kg

Astronomical Unit

Earth

AU

1.496 × 10¹¹

m

Light Year

Earth

ly

9.461 × 10¹⁵

m

Standard Atmosphere

Other

atm

101,325

Pa

Speed of Sound (air, 20°C)

Other

vₛ

343

m/s

Water Density (4°C)

Other

ρ

1000

kg/m³