Generally speaking, it takes about 1lb of CO2 to dispense a full 1/2 barrel keg (1 barrel = 31 US gallons / 1/2 barrel = 15.5 gallons). If you're dispensing a smaller keg, we can work backwards from there. It will take about 1/2lb of CO2 to dispense a 1/4 barrel keg (7.75 gallons) and about 1/3lb CO2 to dispense a 5 gallon keg (corny keg / sixtel).
Refer to the chart below to approximate the number of kegs that can be served from different size CO2 tanks.
Keg Size / Style
|
20oz Cylinder |
1.5 lb Cylinder |
2.5 lb Cylinder |
5 lb Cylinder |
10 lb Cylinder |
15 lb Cylinder |
20 lb Cylinder |
| Corny Keg / Home Brew (5.00 Gallon) |
2-3 |
2-3 |
7-11 |
15-22 |
31-44 |
46-66 |
62-87 |
| Sixth Barrel (5.23 Gallon) |
1-3 |
2-3 |
6-11 |
14-21 |
29-42 |
44-63 |
59-83 |
| Quarter Barrel (7.75 Gallon) |
1-2 |
2-3 |
5-7 |
10-14 |
20-28 |
30-42 |
40-56 |
| Half Barrel (15.50 Gallon) |
N/A |
1 |
2-4 |
5-7 |
10-14 |
15-21 |
20-28 |
* Note that this table should only be used for reference and as an approximation. Actual results may vary.