An amagat (denoted amg or Am[1]) is a practical unit of volumetric number density.
Although it can be applied to any substance at any conditions, it is defined as the number of ideal gas molecules per unit volume at 1 atm (101.325 kPa) and 0 °C (273.15 K).
The amg unit for number density can be converted to the SI unit of moles per cubic meter (mol/m3) by the formula
where The number density of an ideal gas at absolute pressure p and absolute temperature T can be calculated as
Number density of an ideal gas (such as air) at room temperature (20 °C) and 1 atm (101.325 kPa) is