A British Gallon and an American Gallon Are Different Sizes
A gallon is a unit of liquid volume. The two versions differ by about twenty per cent, which matters for fuel economy figures.
A gallon is a unit of liquid volume. Two incompatible versions survive: the imperial gallon is about 4.55 litres, the US gallon about 3.79. The gap is roughly twenty per cent, which is why British and American miles-per-gallon figures cannot be compared directly, and why a US pint is smaller than a British one.
- A unit of volume. *Five gallons of fuel.*
- A large quantity. *Gallons of tea.*
- Gallon as a modifier. *A gallon jug.*
Word forms
| Form | Word | Example |
|---|---|---|
| Noun | gallon | One gallon. |
| Plural | gallons | Ten gallons. |
| Imperial | 4.546 litres | The British gallon. |
| US | 3.785 litres | The American gallon. |
| Related | quart | A quart of milk. |
How it is used in a sentence
- Forty miles per gallon.Which gallon matters.
- A US pint is sixteen fluid ounces.A British pint is twenty.
- He drank gallons of coffee.Figurative exaggeration.
Imperial and US liquid measures
- Gallon — imperial 4.546 litres, US 3.785
- Quart — a quarter gallon in both systems
- Pint — imperial 568 ml, US 473 ml
- Fluid ounce — imperial slightly smaller than US, confusingly
- Origin of the split — the US kept an older English wine gallon, Britain standardised in 1824
From Old North French *galon*, from Medieval Latin *galleta*, a jug or measure. Britain defined the imperial gallon in 1824.
Why do the two gallons differ?
America kept an older English wine gallon, while Britain standardised on a new imperial gallon in 1824.
Which pint is bigger?
The imperial pint, at 568 millilitres, against the US pint's 473. A British pint is about a fifth larger.