A US gallon is 3.785 liters; a UK gallon is 4.546 liters. They share a name but not a size, so the calculator shows both, together with quarts, pints, fluid ounces and cubic meters.
Gallons to liters
| Gallons | US gallons in liters | UK gallons in liters |
|---|---|---|
| 1 | 3.79 | 4.55 |
| 2 | 7.57 | 9.09 |
| 3 | 11.36 | 13.64 |
| 5 | 18.93 | 22.73 |
| 10 | 37.85 | 45.46 |
| 12 | 45.42 | 54.55 |
| 15 | 56.78 | 68.19 |
| 20 | 75.71 | 90.92 |
| 50 | 189.27 | 227.30 |
| 100 | 378.54 | 454.61 |
Liters to gallons
| Liters | US gallons | UK gallons |
|---|---|---|
| 1 | 0.264 | 0.220 |
| 4 | 1.057 | 0.880 |
| 5 | 1.321 | 1.100 |
| 10 | 2.642 | 2.200 |
| 20 | 5.283 | 4.399 |
| 40 | 10.567 | 8.799 |
| 50 | 13.209 | 10.998 |
| 60 | 15.850 | 13.198 |
| 100 | 26.417 | 21.997 |
A typical car fuel tank of 50 liters holds 13.2 US gallons, or 11 UK gallons.
Fuel economy: miles per gallon to liters per 100 km
Fuel economy is the one conversion that runs backwards: more miles per gallon means fewer liters per 100 km. And because the gallons differ, the same car has two mpg figures – one on a US window sticker, a higher one in a UK brochure.
| Miles per gallon | L/100 km (US mpg) | L/100 km (UK mpg) |
|---|---|---|
| 15 | 15.7 | 18.8 |
| 20 | 11.8 | 14.1 |
| 25 | 9.4 | 11.3 |
| 30 | 7.8 | 9.4 |
| 35 | 6.7 | 8.1 |
| 40 | 5.9 | 7.1 |
| 50 | 4.7 | 5.6 |
| 60 | 3.9 | 4.7 |
The formulas: L/100 km = 235.215 ÷ US mpg, or 282.481 ÷ UK mpg. A car rated at 40 mpg in Britain uses 7.1 L/100 km, which in the US would be quoted as 33.3 mpg.
Smaller measures
| Unit | US | UK |
|---|---|---|
| Quart (¼ gallon) | 0.946 L | 1.137 L |
| Pint (⅛ gallon) | 0.473 L | 0.568 L |
| Fluid ounce | 29.57 mL | 28.41 mL |
| Fluid ounces in a pint | 16 | 20 |
A British pint of beer (568 mL) is about 20% larger than an American one (473 mL), and the UK pint has 20 fluid ounces against 16 in the US.
Oil barrels
Crude oil is traded in barrels of 42 US gallons, which is 158.99 liters. The converter in the unit list includes it, so a price per barrel can be turned into a price per liter: divide by 159.
At a gas station abroad with no data, the converter still works once zet4u is saved on your phone (how it works offline).
Frequently asked questions
How many liters are in a gallon?
It depends on the gallon. A US gallon is 3.785411784 liters; a UK (imperial) gallon is 4.54609 liters, about 20% more.
How do I convert miles per gallon to liters per 100 km?
Divide 235.215 by US miles per gallon, or 282.481 by UK miles per gallon. 30 US mpg is 7.84 L/100 km; 30 UK mpg is 9.42 L/100 km.
How many gallons are in 50 liters?
13.21 US gallons, or 11.00 UK gallons.
Why is a UK gallon bigger than a US gallon?
The US kept the old English wine gallon of 231 cubic inches; Britain redefined its gallon in 1824 as the volume of 10 pounds of water. The two have been different ever since.
Sources
- NIST Special Publication 811: Guide for the Use of the SI, Appendix B (conversion factors)
- UK Weights and Measures Act 1985, Schedule 1
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