<P> The US gallon is legally defined as 231 cubic inches, which is exactly 7000378541178400000 ♠ 3.785 411 784 liters . 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 ⁄ of a US gallon . In order to overcome the effects of expansion and contraction with temperature when using a gallon to specify a quantity of material for purposes of trade, it is common to define the temperature at which the material will occupy the specified volume . For example, the volume of petroleum products and alcoholic beverages are both referenced to 60 ° F (16 ° C) in government regulations . </P> <P> This dry measure is one - eighth of a US Winchester bushel of 7003215042000000000 ♠ 2150. 42 cubic inches; it is therefore equal to exactly 268.8025 cubic inches or about 6997440500000000000 ♠ 4.405 L. The US dry gallon is not used in commerce, and is not listed in the relevant statute, which jumps from the dry quart to the peck . </P> <P> The Imperial gallon was used in everyday life (and in advertising) in the United Kingdom until 1994, and less frequently in Canada, including fuel economy expression in advertisements and other official publications . Gallons used in fuel economy expression in Canada and the United Kingdom are Imperial gallons . </P> <P> The gallon was removed from the list of legally defined primary units of measure catalogued in the EU directive 80 / 181 / EEC for trading and official purposes, with effect from 31 December 1994 . Under the directive the gallon could still be used--but only as a supplementary or secondary unit . One of the effects of this directive was that the United Kingdom amended its own legislation to replace the gallon with the litre as a primary unit of measure in trade and in the conduct of public business, effective from 30 September 1995 . </P>

When did uk change from gallons to litres