Percentage Oxygen in Earth's Atmosphere

Not Reviewed
Constant / Last modified by KurtHeckman on 2017/10/06 16:04
`O_"ATM" = 20.95 %`
MichaelBartmess.Percentage Oxygen in Earth's Atmosphere

The Earth has 20.95% Oxygen by volumetric percentage of Oxygen present in a sample of the Earth's atmosphere.  Dry air by volume contains the following major constituents:

  • 78.09% nitrogen
  • 20.95% oxygen
  • 0.93% argon
  • 0.039% carbon dioxide

The amount of water vapor contained in air is on average 1% but varies.  (Humidity is a pain; gotta love Colorado.)