How much oxygen is contained in Earth's atmosphere?

Question

...Is there a way to measure the volume of the oxygen on earth?...

Answer 1

Earth's atmosphere is made up of 20.9463% oxygen.

Answer 2

Percentage wise, the atomsphere consists of 20.9% Oxygen and about 78% Nitrogen.  The remainder is mostly Argon and Carbon Dioxide.

If you are interested in estimating the volume of air on earth, first find the volume of the atompsphere and 20.9% of that volume would be roughly the volume of oxygen.  To get a rough estimate of the volume of the atompshere, you can use this simple equation, (4/3)*pi*(R^3-r^3) where R is the radius of the atmosphere and r is the radius of the earth.

This would give you only a very rough estimate because the earth's atmosphere varies in composition with altitude and the density of the atmosphere changes significantly, so your volume calculation really couldn't be converted to mass easily, but it will probably give you a ball park figure.

Answer 3

30%