Comparison of the imperial and US customary measurement systems adopted a system based on the 231-cubic-inch wine gallon for all fluid purposes. This became the US fluid gallon. Both the imperial and US fluid gallon are divided into 4 quarts, 8 pints or 32 gills. However, whereas the US gill is divided into 4 US fluid ounces, the imperial gill is divided into 5 imperial fluid ounces. So whilst the imperial gallon, quart, pint and gill are about 20% larger than their US fluid measure counterparts, the fluid ounce is about 4% smaller. Note that one avoirdupois ounce of water has an approximate volume of one imperial fluid ounce
Keg UK and Ireland is quite different, whilst the couplers for kegs have been largely standardised to sankey, grundy and interbrew, a couple of others exist such as UEC and U-Type; however these are much less common. The kegs themselves are made from stainless steel or aluminium. The standard keg size is 11 imperial gallons (50 litre/88 imperial pints approx) and the vast majority of keg beers are supplied in this keg size. There are also smaller 30 liters (52.76 imperial pints) kegs usually reserved for more specialist and/or premium European beers. A number of manufacturers also produce 18 imperial gallon