A keg is not one size. In the United States everything is a fraction of the
US beer barrel, which is defined as exactly 31 US liquid gallons
(117.35 litres). In Europe kegs are sold in round metric volumes instead —
50 L, 30 L and 20 L. That single difference explains why a "full size" keg
means 15.5 gallons in Denver and 50 litres in Düsseldorf.
Quick answer
A standard US keg (half barrel) holds 15.5 US gallons = 58.67 litres = 1,984 fl oz,
which pours about 124 pints of 16 oz or 165 bottles of 12 oz.
Every keg size compared
| Keg | US gallons | Litres | US fl oz | 16 oz pints | 12 oz servings |
|---|---|---|---|---|---|
| Half barrel (standard) | 15.5 | 58.67 | 1,984 | 124 | 165 |
| 50 L Euro keg | 13.2 | 50.0 | 1,690 | 105 | 140 |
| Quarter barrel (pony) | 7.75 | 29.34 | 992 | 62 | 82 |
| Slim quarter (tall quarter) | 7.75 | 29.34 | 992 | 62 | 82 |
| 30 L Euro keg | 7.93 | 30.0 | 1,014 | 63 | 84 |
| Sixth barrel (sixtel) | 5.16 | 19.55 | 661 | 41 | 55 |
| Cornelius (corny) keg | 5.0 | 18.93 | 640 | 40 | 53 |
| 20 L Euro keg | 5.28 | 20.0 | 676 | 42 | 56 |
| Mini keg (bubba) | 1.32 | 5.0 | 169 | 10 | 14 |
Serving counts assume a clean pour with roughly one pint of foam loss per keg.
In practice a busy bar loses 3–5% of a keg to foam and line cleaning.
Weight and dimensions
Weight decides whether one person can carry the keg and whether it fits your
kegerator. Stainless kegs weigh a lot empty, and beer is slightly denser than
water (about 1.01 kg/L).
| Keg | Empty weight | Full weight | Height × diameter |
|---|---|---|---|
| Half barrel | 29.7 lb (13.5 kg) | 160.5 lb (72.8 kg) | 23.3 in × 16.1 in |
| Quarter barrel | 22 lb (10 kg) | 87 lb (39.5 kg) | 13.9 in × 16.1 in |
| Slim quarter | 22 lb (10 kg) | 87 lb (39.5 kg) | 23.3 in × 11.1 in |
| Sixth barrel | 16.5 lb (7.5 kg) | 58 lb (26.3 kg) | 23.3 in × 9.25 in |
| Cornelius keg | 9 lb (4.1 kg) | 55 lb (25 kg) | 25 in × 8.5 in |
| 50 L Euro keg | 30 lb (13.6 kg) | 140 lb (63.5 kg) | 20.9 in × 15.2 in |
To weigh what is left in a keg, subtract the empty (tare) weight and divide by
8.34 lb per gallon — beer is close enough to water for bar maths.
US vs European kegs
- US kegs are barrel fractions. 1/2, 1/4 and 1/6 of a 31 gallon barrel.
- Euro kegs are metric. 50 L, 30 L and 20 L, so nothing lines up neatly
with gallons: a 50 L keg is 13.2 gallons, not 15.5.
- UK casks are different again. A UK firkin is 9 imperial gallons
(40.9 L) and a kilderkin is 18 imperial gallons (81.8 L).
- Imperial and US gallons are not the same: 1 imperial gallon = 1.201 US
gallons. Use the gallon converter before trusting
any figure quoted without a country.
Coupler types (they are not interchangeable)
| Coupler | System | Typical brands |
|---|---|---|
| D | American Sankey | Most US domestic and craft beer |
| S | European Sankey | Heineken, Beck's, Stella Artois |
| A | German slider | Warsteiner, Spaten, Bitburger |
| M | German slider (alt.) | Paulaner, Ayinger |
| G | Grundy / UK | Bass, Boddingtons, Anchor |
| U | U-system | Guinness, Harp, Kilkenny |
Forcing the wrong coupler onto a keg valve will not seal, and can vent the keg.
Check the brand before you rent the tap.
How many kegs do I need?
Plan on two drinks per guest in the first hour and one per hour after that.
A four-hour party for 50 guests is roughly 250 servings — that is one and a
half half barrels, or two if you want to be safe.
- 20 guests, 3 hours ≈ 80 servings ≈ one quarter barrel
- 50 guests, 4 hours ≈ 250 servings ≈ two half barrels
- 100 guests, 4 hours ≈ 500 servings ≈ three half barrels
Serving temperature and pressure
Most US ales and lagers pour best at 38 °F (3.3 °C) with 10–12 psi of
CO₂ on a 5 ft beer line. Warm beer foams: every 2 °F above target roughly
doubles the foam you lose. Convert your target with the
Fahrenheit to Celsius converter.
Keg size guides
- Half barrel keg — the 15.5 gallon standard
- Quarter barrel / pony keg — 7.75 gallons
- Sixtel keg — 5.16 gallons, the craft standard
- Cornelius (corny) keg — the 5 gallon homebrew keg
Key takeaways
- A US half barrel is 15.5 gallons / 58.67 L / 124 pints — the default "keg".
- A 50 L European keg is smaller than a US half barrel, not equal to it.
- A sixtel is the best fit for a home kegerator; a corny keg is the homebrew standard.
- Couplers are brand-specific — confirm D, S, A, M, G or U before tapping.