Ambient Temp dependent.
A Colemans Propane Bottle will do roughly -
30 on GHK G5 Mags
35 on Prowin V2's
20-30 on WE M4 Mags
35-40 on WE SMG8 Mags
30-40 on G&P PMags
20-25 KWA Vector Mags
A WE Green Gas will do roughly -
15 - G5
15-20 - Prowin
10-15 WE M4 Mags
15 - SMG8 Mags
20 - PMags
~10 - Vectors
These are all taken from practice, Propane, even with colemans tanks works out a helluva lot cheaper. However, quite a few sites near me for example, have blanket bans on Propane for BS reasons (basically to sell their own stock at exorbitant prices)
The other thing you've got to factor in, with mags with exceptionally long gas times (cough, vector) the WE Green fill tip actually freezes shut, rendering the can unusable, where as using the AI propane adapter, negates the problem as its made from polymer rather than metal. Oh and the Madbull adapter, steer well clear of, its junk.