Density of Air
Why is Air Density important?
Any object suspended in a fluid is subject to two opposing vertical forces, gravity is pulling it downwards, whilst fluid buoyancy is pushing it upwards.
The buoyancy effect – commonly known as Archimedes’ Principle – is widely recognised in water or other fluids, but very few are aware that air also imparts a buoyancy force on objects due to the same effect.
In many day-to-day weighing applications, this air buoyancy effect is insignificant, however in high precision weighing applications it becomes a crucial consideration.
The density of air is an important parameter in the calculation of air buoyancy. Air density is calculated using four parameters: temperature, pressure, relative humidity, and carbon dioxide level.
For more information about air density, air buoyancy, and their implications for mass measurement, please see Calculating Air Density.
Density of Air Calculator
The Density of Air Calculator has been designed to calculation of an air density value at any atmospheric conditions one might reasonably encounter in any weighing laboratory around the world. The calculator allows three variables – temperature, pressure, and relative humidity – to be set. A carbon dioxide content of 400 parts per million (mean CO2 content of fresh air) is assumed.
The calculator is based on the CIPM-2007.¹ It is freely available, however we do request that any subsequent use of this work be acknowledged in the form of appropriate references.