Physical Constants
Physical constants in SI Units - Reference table with values and formulas
| Description | Symbol | Formula | Value (SI) | Unit |
|---|---|---|---|---|
| Absolute zero, temperature | 0 K / -273.15 °C | K | ||
| Acceleration of gravity at earth's surface | g | 9.81 | m/s² | |
| Atmospheric pressure at sea level | 1.01325×10⁵ | N/m² | ||
| Atomic mass unit | 1.660540×10⁻²⁷ | kg | ||
| Avogadro's constant | Nₐ | 6.022141×10²³ | mol⁻¹ | |
| Base of natural logarithms | e | 2.718281828 | ||
| Bohr magneton | μB | e h/4πmₑ | 9.274009994×10⁻²⁴ | Am² |
| Bohr radius | a₀ | ε₀h²/π mₑe² | 5.2917721067×10⁻¹¹ | m |
| Boltzmann constant | k | R/Nₐ | 1.38064852×10⁻²³ | J/K |
| Charge of electron | e | 1.602176×10⁻¹⁹ | C | |
| Faraday constant | F | e Nₐ | 9.648533289×10⁴ | C/mol |
| Fine structure constant | α | 7.29720×10⁻³ | ||
| Gas constant (molar, ideal) | R | 8.3144598 | J/mol·K | |
| Gravitational constant | G | 6.67408×10⁻¹¹ | m³/kg·s² | |
| Mass of electron (rest mass) | mₑ | 9.10938356×10⁻³¹ | kg | |
| Mass of neutron | mₙ | 1.67492747×10⁻²⁷ | kg | |
| Mass of proton | mₚ | 1.67262190×10⁻²⁷ | kg | |
| Permeability of a vacuum | μ₀ | 4π×10⁻⁷ | H/m | |
| Permittivity of a vacuum | ε₀ | 1/μ₀c₀² | 8.854187817×10⁻¹² | F/m |
| Planck's constant | h | 6.626070040×10⁻³⁴ | J·s | |
| Radiation constant, first | C₁ | 2πhc² | 3.741844×10⁻¹⁶ | W·m² |
| Radiation constant, second | C₂ | hc/k | 1.438833×10⁻² | m·K |
| Ratio of a circle's circumference to diameter | π | C/d | 3.141592653 | |
| Rydberg constant | R∞ | mₑe⁴/8ε₀²h³c₀ | 1.097373156×10⁷ | m⁻¹ |
| Speed of light in vacuum | c₀ | 2.99792458×10⁸ | m/s | |
| Stefan-Boltzmann constant | σ | 5.670367×10⁻⁸ | W/m²·K⁴ | |
| Volume ideal gas, 1 atm, 0°C | Vₘ | 22413.6 cm³/mol | cm³/mol | |
| Volume ideal gas, 1 atm, 25°C | Vₘ | 24466.1 cm³/mol | cm³/mol |