Fundamental Constants
The fixed numbers the universe runs on. Values below follow the SI definitions; never guess a constant — look it up.
Atomic mass unit (dalton) (u (Da))
1.66053906660×10⁻²⁷ kg kg
Avogadro constant (N_A)
6.02214076×10²³ mol⁻¹ mol⁻¹
Boltzmann constant (k_B)
1.380649×10⁻²³ J/K J/K
Elementary charge (e)
1.602176634×10⁻¹⁹ C C
Faraday constant (F)
96485 C/mol C/mol
Molar gas constant (R)
8.314 J/(mol·K) J/(mol·K)
Planck constant (h)
6.62607015×10⁻³⁴ J·s J·s
Speed of light in vacuum (c)
299792458 m/s m/s
Ion product of water (K_w)
1.0×10⁻¹⁴ at 25 °C unitless (activity-based)