What is a keg?
A keg is a small barrel or vessel. Their primary function is to store, transport and serve beer.
Beer keg size
Traditionally a full-sized keg is 15.5 gallons, the equivalent to 124 pints or 165 bottles. Keg beer (Lager) is different from Cask beer (Ale), and not to be confused. Casks come in different sizes, the largest is a Barrel which contains 36 gallons. A half-sized barrel is called a Kilderkin and can hold 18 gallons. As you can imagine, these measures are commonly used by bars and restaurants for large scale commercial trade.
Kegs of beer for home use, commonly referred to as “mini-kegs” are typically 5 litres. This is roughly 9 pints.