Physical Constants
Exact and recommended values from CODATA 2018 / SI 2019 redefinition.
| Quantity | Symbol | Value | Unit |
|---|---|---|---|
| Speed of light in vacuum | c | 299,792,458 | m/s |
| Gravitational constant | G | 6.67430 × 10⁻¹¹ | N·m²/kg² |
| Planck constant | h | 6.62607015 × 10⁻³⁴ | J·s |
| Reduced Planck | ℏ | 1.054571817 × 10⁻³⁴ | J·s |
| Elementary charge | e | 1.602176634 × 10⁻¹⁹ | C |
| Avogadro number | Nₐ | 6.02214076 × 10²³ | mol⁻¹ |
| Boltzmann constant | k | 1.380649 × 10⁻²³ | J/K |
| Gas constant | R | 8.314462618 | J/(mol·K) |
| Electron mass | mₑ | 9.1093837015 × 10⁻³¹ | kg |
| Proton mass | mₚ | 1.67262192369 × 10⁻²⁷ | kg |
| Standard gravity | g₀ | 9.80665 | m/s² |
| Stefan–Boltzmann | σ | 5.670374419 × 10⁻⁸ | W/(m²·K⁴) |