Summary: In Great Britain, a spirit measure for gin, rum, vodka or whisky is either 25 ml or 35 ml, and multiples thereof; both sizes cannot be used on the same premises.
Reference: Weights and measures: the law (opens in a new tab)
Department for Business and Trade · Reference checked 21 July 2026
Where to look: Specified quantities: Alcohol: By the glass
The summary above is a concise paraphrase of the cited material. It is not a quotation or a complete statement of law.
Glossary last reviewed .