☙

imperial gallon

Convert imperial (UK) gallons to current major units of capacity

In Great Britain, 1824–20ᵗʰ century, a unit of capacity, by the Weights and Measures Act of 1985, exactly “4.54609 cubic decimeters” (i.e., liters as currently defined), approximately 277.4193 cubic inches. The unit was defined by Act 5 George IV c 74 1824 as the volume of 10 Avoirdupois pounds of water at 62°F. See imperial system of weights and measures. Abbreviation, “gal”.

The 1963 Weights and Measures Act defined the imperial gallon as exactly 4.545 964 591 liters, and the yard as exactly 0.9144 meter, so between 1963 and the 1976 Weights and Measures Act the imperial gallon was exactly 277.411 779 864 898 cubic inches.

The imperial gallon was also subdivided to create British apothecaries' measure. Symbol in pharmaceutical contexts, “C”.¹

1. Balances, Weights and Measures.
Information Sheet 11.
Museum of the Royal Pharmaceutical Society of Great Britain.