The English system gallons
There were more than a few systems of liquid measurements in the pre-1884 United Kingdom.[1]
Winchester or Corn Gallon was 272 in³ (157 fl oz) (1697 Act 8 & 9 Will III c22)
Henry VII (Winchester) corn gallon from 1497 onwards was 154.80 fl oz
Elizabeth I corn gallon from 1601 onwards was 155.70 fl oz
William III corn gallon from 1697 onwards was 156.90 fl oz
Old English (Elizabethan) Ale Gallon was 282 in³ (162 fl oz) (1700 Act 11 Will III c15)
Old English (Queen Anne) Wine Gallon was standardized as 231 in³ (133 fl oz) in the 1706 Act 5 Anne c27, but it differed before that:
London ‘Guildhall’ gallon (before 1688) was 129.19 fl oz
Jersey gallon (from 1562 onwards) was 139.20 fl oz
Guernsey gallon (17th century origins ‘til 1917) was 150.14 fl oz
Irish Gallon was 217 in³ (125 fl oz) (1495 Irish Act 10 Hen VII c22 confirmed by 1736 Act Geo II c9)
The Imperial gallon
The imperial (UK) gallon, now defined as exactly 4.54609 litres (about 277.42 cubic inches), is used in some Commonwealth countries and was originally based on the volume of 10 pounds (approximately 4.54 kg) of water at 62 °F (17 °C). The imperial fluid ounce is defined as 1⁄160 of an imperial gallon; there are four quarts in a gallon, two pints in a quart, and 20 Imperial fluid ounces in an imperial pint.
The US liquid gallon
The US gallon is legally defined as 231 cubic inches, which is exactly 3.785411784 liters.[2][3] A US liquid gallon of water weighs about 8.34 pounds or 3.78 kilograms at 62 °F (17 °C), making it about 16.6% lighter than the imperial gallon. There are four quarts in a gallon, two pints in a quart and 16 US fluid ounces in a US pint, which makes the US fluid ounce equal to 1⁄128 of a US gallon.