Table of exact SI physical constants and standard values: Avogadro constant, gas constant in several units, Planck, Boltzmann, Faraday, standard gravity and molar volume.
| Quantity | Symbol | Value | Unit |
|---|---|---|---|
| Speed of light in vacuum | c | 299 792 458 | m/s |
| Planck constant | h | 6.626 070 15 × 10⁻³⁴ | J·s |
| Elementary charge | e | 1.602 176 634 × 10⁻¹⁹ | C |
| Boltzmann constant | kB | 1.380 649 × 10⁻²³ | J/K |
| Avogadro constant | NA | 6.022 140 76 × 10²³ | mol⁻¹ |
| Gas constant | R = NA·kB | 8.314462618 | J/(mol·K) |
| Gas constant | R | 0.0820574 | L·atm/(mol·K) |
| Gas constant | R | 1.987204 | cal/(mol·K) |
| Faraday constant | F = NA·e | 96485.33212 | C/mol |
| Stefan–Boltzmann constant | σ | 5.670374419 × 10⁻⁸ | W/(m²·K⁴) |
| Standard gravity | gn | 9.806 65 | m/s² |
| Standard atmosphere | atm | 101 325 | Pa |
| Molar volume of an ideal gas (0 °C, 1 atm) | Vm | 22.4140 | L/mol |
| Molar volume of an ideal gas (0 °C, 1 bar) | Vm | 22.7110 | L/mol |
| Molar volume of an ideal gas (25 °C, 1 atm) | Vm | 24.4654 | L/mol |
| Absolute zero | 0 K | −273.15 | °C |
| Ion product of water (25 °C) | Kw | 1.0 × 10⁻¹⁴ | — |
Exact: value fixed by definition in the SI (2019) or by convention (g_n, atm). The others are computed from them (R in other units with 1 atm = 101.325 kPa and 1 cal = 4.184 J). K_w is the rounded value used by the pH tools.
Source: International System of Units (SI), 9th edition (2019): exact defining constants. ↗
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