How to use the keg pours calculator
- Choose the keg size, or pick "my own size" and enter its volume.
- Enter the pour size and the foam and waste allowance, which is the share of the keg you expect to lose to foam, purging and dregs.
- To plan an event, keep the box ticked and enter the guests who will have a serving, the event length and the servings per guest per hour.
- Read the servings per keg, the number of kegs to order and the servings left over. In the advanced options, add a price per keg for a cost per serving.
Formula
usable volume = keg volume x (1 - foam and waste share)
servings per keg = round down(usable volume / pour size)
servings needed = guests x hours x servings per guest per hour
kegs = round up(servings needed / servings per keg)
A US half barrel holds 15.5 gallons, which is 1,984 fluid ounces. A pour is counted only when a full pour is left.
A half barrel and 60 guests
A half barrel holds 1,984 fl oz, which is 165.3 pours of 12 fl oz before any loss. With a 5 percent allowance for foam and waste, 1,884.8 fl oz is usable and the keg gives 157 pours. For 60 guests over 4 hours at one serving per hour, 240 servings are needed, which takes 2 kegs.
A sixth barrel (5.17 gallons) with 16 fl oz pints gives 39 pours. A 50 liter keg gives 133 pours of 12 fl oz. If a keg costs $180, each of the 157 pours costs $1.15.
Keg sizes and loss
Common US keg sizes are the half barrel (15.5 gallons), the quarter barrel (7.75 gallons) and the sixth barrel (about 5.17 gallons). European kegs are measured in liters, with 50 and 30 liter sizes. Sizes are nominal and can vary a little by maker. The first pours often run foamy, and the last part of a keg is usually not worth pouring, so an allowance of a few percent is sensible. Your own figure depends on temperature, pressure, line length and skill.
For the rest of the party, see the party food and drink calculator and the birthday party cost calculator. If you brew, the SRM beer color calculator and the mash strike water calculator cover two steps earlier in the process.
Planning with care
Guests drink at very different rates, so the servings per guest per hour is an example you can change, and some guests will have none. Plan water and non-alcoholic drinks too, check the rules for serving alcohol where you are, and arrange safe rides home.
Assumptions and limits
- The keg sizes are nominal US and metric sizes. A fluid ounce is the US fluid ounce, and a gallon is the US gallon of 128 fluid ounces.
- The foam and waste share is an allowance you choose. The default is an example value.
- The servings per guest per hour is an example value and is the same for every guest.
- Prices are optional and shown in dollars.
Frequently asked questions
How many pints are in a half barrel?
A half barrel holds 1,984 US fluid ounces, which is 124 pints of 16 ounces before any loss. With a 5 percent allowance for foam and waste, you can expect about 117 full pints.
Should I round the kegs up?
Yes, because you cannot order part of a keg. The page rounds up and shows the servings left over so you can see the cushion. If a keg can be returned unopened, ordering one more is a low-risk choice.
Does the pour size include the foam?
The pour size is what the guest receives. The allowance for foam and waste is taken from the keg before servings are counted.
What about CO2 and cooling?
They are not part of this calculator. Ask your supplier about gas, taps and cooling for the size of keg you choose.