Gallons to Litres Converter

This converter turns US gallons — the volume unit on American fuel quotes, car specs, large drink containers and many imported products — into litres, the unit used on every UK forecourt and supermarket shelf. Note this is the US liquid gallon (3.78541 L); the UK imperial gallon is 20% larger at 4.54609 L.

The formula in plain English: multiply the number of US gallons by 3.78541 to get litres. The relationship is exact by definition — 1 US gallon = 231 cubic inches = 3.785411784 litres. For mental maths, "× 3.8" is within 0.1%.

Worked example. A US car spec sheet quotes a 16-gallon fuel tank. Multiply 16 × 3.78541 ≈ 60.6 litres — about the size of a typical mid-sized family car tank in the UK. A US recipe asking for "1 gallon of stock" needs 3.79 litres in metric terms. A 5-gallon water cooler bottle is 18.93 L — roughly the same size as a standard UK office cooler bottle (which is usually labelled 18.9 L).

Why this matters. Fuel economy is the classic trap: a US car listed at "25 mpg" sounds worse than a UK car at "30 mpg", but the gallons aren't the same size. Converting back to litres-per-100-km (the European standard) shows the truth. The same applies to imported tanks, water containers and recipe volumes — the headline number means something different in each system.

When to use it. Translating US fuel-tank capacities, converting American recipe volumes, sizing imported drinks dispensers, and comparing US gallons of paint, chemicals or cleaning products against UK litre-based products.

When not to rely on it alone. If a US source mentions "gallons" without specifying, it almost always means US gallons — but old British and Commonwealth sources usually mean imperial gallons. Always identify which system before converting.

Common mistakes. Treating UK and US gallons as the same (they differ by 20%). Converting US fl oz to ml using the UK figure (US fl oz = 29.6 ml; UK fl oz = 28.4 ml — small difference but it accumulates in baking). Forgetting that paint coverage on US tins is quoted per US gallon, so when comparing with UK paint priced per litre you need to convert first.