air expansion or compression formula?

[bobbybuttr]

A question for mathematic people. What is the air expansion formula for ascents? I know its not liner since air expands or compresses more in the first few feet than when a person is deeper. Specifically I would like to be able to determine the expansion at different depth to the surface. Say 6 feet to the surface.
Thanks,
Bobby

 

[Bill]

If I understand it right, expansion is linear in atmospheres. Six feet is 6/32.8+1 or 1.18 atm. and expansion to the surface should be almost 20%.
Aloha
Bill

 

[bobbybuttr]

Thanks Bill,
That formula works when I use the known 33, 66, and 99 depths.
Bobby