Imperial Gallons to Liters (gal (UK) to L)

1 imperial gallon equals 4.54609 liters exactly.

1 imperial gallon = 4.54609 liters

How to convert imperial gallons to liters

To convert imperial gallons to liters, multiply the number of imperial gallons by 4.54609. This factor is exact. To go the other way, multiply liters by 0.2199692483 (rounded).

liters = imperial gallons × 4.54609

Example: 10 imperial gallons = 45.4609 liters.

Pints, quarts, gallons and fluid ounces differ between the US and the UK. Units are labeled 'US' or 'imperial' to avoid confusion.

About these units

Imperial Gallon (gal (UK))

Imperial (British)Current unit

Exactly 4.54609 liters, the volume of 10 pounds of water. Used for fuel economy in the UK (miles per gallon) and historically across the Commonwealth.

Britain unified its confusing gallons by act of Parliament in 1824. Before then, the country used separate ones for wine at 231 cubic inches, ale at 282 and corn at about 268.8. The 1824 reform replaced them with the imperial gallon, defined as the volume of ten pounds of distilled water, calculated at 277.274 cubic inches. A new definition in 1889 slightly changed that, and after the liter was restored to exactly a cubic decimeter in 1964, Canada and then the UK in 1976 adopted the exact value of 4.54609 liters.

Because the United States kept the 231-cubic-inch wine gallon, an imperial gallon is about 20 percent larger than a US gallon. That explains why a car rated at 40 miles per gallon in Britain is less impressive in American terms, since it comes to roughly 33 US miles per gallon. Ireland dropped the gallon as a primary trade unit at the end of 1993 and the UK at the end of September 1995, but it lives on in British fuel-economy figures and older recipes.

1 imperial gallon = 4.54609 liters (exactly).

Sources: Wikipedia: Gallon; UK Weights and Measures Act 1985, Schedule 1

Liter (L)

Metric (SI)Current unit

One cubic decimeter (1,000 cm³). The everyday metric unit of volume for drinks, fuel and cooking.

The liter was born in revolutionary France. In 1795 it was introduced as a republican unit and defined as one cubic decimeter, while the gram was tied to a cubic centimeter of water. The name comes from the older French litron, itself descended from a Byzantine Greek unit of weight, not volume. A small revision of the decimeter in 1798 left the first liter about 1.000974 of today's cubic decimeter, and in 1879 the international metric authorities adopted the liter with the symbol l.

The liter then took a strange detour. In 1901 it was redefined as the space taken up by one kilogram of pure water at its densest, which made it about 1.000028 cubic decimeters, and that muddled definition lasted until 1964, when it was restored to exactly one cubic decimeter. A capital L was added as an alternative symbol in 1979 because a lowercase l is easy to mistake for the digit 1, and NIST says L is the symbol to use in the United States. A liter of water is close to a kilogram, which is why a one-liter bottle feels like a kilo in the hand.

The liter is the reference unit for volume on this site.

Sources: Wikipedia: Litre; NIST Guide to the SI, Chapter 5: units outside the SI

Related conversions

See all volume units.