Generally used constants and notations in physics for calculations of different. It is a set of fundamental invariant quantities observed in nature and appearing in the basic theoretical physics equations.

Accurate evaluation of these constants is essential to check the correctness of the theories and to allow user applications to be made on the basis of those theories.

The constants listed below are known values of physical constants expressed in standard international units (SI units); that is, physical quantities, these are generally believed to be universal in nature and thus are independent of the unit system in which they are measured. These constants must be known to as high an accuracy as possible.

## Space and universe

Gravitational constant (G) = 6.67 x 10^{-11} N m^{2} kg^{-2}

Speed of light in vacuum (c) = 3 x 10^{8} ms^{-1}

Permeability of vacuum (µ_{0}) = 4π x 10^{-7} H m^{-1}

Permittivity of vacuum (ε_{0}) = 8.85 x 10^{-12} F m^{-1}

Acceleration due to gravity (g) = 8.806 ms^{-2}

Planck constant (h) = 6.63 x 10^{-34} Js

## Atom and electron

Energy equivalent of 1 amu = 931.5 MeV

Electron rest mass (m_{e}) = 9.1 x 10^{-31} kg ≡ 0.511 MeV

Electron mass (m_{e}) = 9.1 x 10^{-31} kg

Proton mass (p_{m}) = 1.6 x 10^{-27} kg

Neutron mass (m_{n}) = 1.6 x 10^{-27} kg

Elementary mass unit = 1.6 x 10^{-27} kg

Nuclear magneton (µ_{N}) = 5.05 x 10^{-27} J/T

Charge on electron (e^{–}) = 1.602 x 10^{-19} C

Avogadro constant (N_{A}) = 6.02 x 10^{23} mol^{-1}

## Current and electricity

Faraday constant (F) = 9.648 x 10^{4} C mol^{-1}

Fine-structure constant (α) = 7.2973525664 × 10^{−3}

## Heat and thermodynamics

Stefan-Boltzman constant (σ) = 5.67 x 10^{-8} W m^{-2} K^{-4}

Wien constant (b) = 2.89 x 10^{-3} mK

Rydberg constant (R_{∞}) = 1.097 x 10^{7} m^{-1}

Triple point for water = 273.16 K (0.01°C)

Molar volume of an ideal gas (at NTP) = 22.4 x 10^{-3} m^{3} mol^{-1}