Amagat

The amg unit for number density can be converted to the SI unit of moles per cubic meter (mol/m³) by the formula $${\displaystyle 1\ {\text{amg }}{\overset {\frown }{=}}\ {\frac {n_{0}}{N_{A}}}\approx 44.615{\text{ mol/m}}^{3},}$$ where

≘ indicates correspondence, since the SI unit is of molar concentration and not number density;

n₀ is the Loschmidt constant;

N_A is the Avogadro constant.

In cgs units, one amagat in units of (number of particles) per cubic centimeter is: $${\displaystyle 1\ {\text{amg }}{\overset {\frown }{=}}2.69\times 10^{19}/{\text{cm}}^{3},}$$

The number density of an ideal gas at absolute pressure p and absolute temperature T can be calculated as $${\displaystyle \eta ={\frac {p}{p_{0}}}\ {\frac {T_{0}}{T}}\ {\text{ amg}},}$$ where T₀ = 273.15 K, and p₀ = 101.325 kPa (STP before 1982).

Number density of an ideal gas (such as air) at room temperature (20 °C) and 1 atm (101.325 kPa) is

${\displaystyle \eta =\left({\frac {1\ {\text{atm}}}{p_{0}}}\right)\left({\frac {273.15\ {\text{K}}}{(273.15+20)\ {\text{K}}}}\right)\ {\text{amg}}=0.932\ {\text{amg}}.}$