How many liters are in a gallon?
Quick answer
There are 3.785 liters in a US gallon and 4.546 liters in a UK (imperial) gallon. For a quick estimate, a US gallon is just under 4 liters.
Fill a US gallon jug with liter bottles and you’d empty almost four of them: 3.785, to be precise. That number is fixed by definition. A US gallon is 231 cubic inches, and since the inch was fixed at exactly 2.54 cm in 1959, that makes it precisely 3.785411784 liters.
Converter
Gallons to liters at a glance
| US gallons | Liters |
|---|---|
| 1 | 3.79 L |
| 2 | 7.57 L |
| 5 | 18.93 L |
| 10 | 37.85 L |
| 20 | 75.71 L |
Going the other way, 1 liter is about 0.264 US gallons, or roughly a quarter of a gallon. That’s very close to a US quart, which holds 0.946 liters.
Why does the UK gallon hold more?
The British imperial gallon was redefined in 1824 as the volume of 10 pounds of water, which came to about 4.546 liters. The US kept an older English wine gallon from the 1700s, which is smaller. So a UK gallon is about 20% larger than a US one.
This matters most for fuel. A car rated at 40 miles per gallon in the UK is using imperial gallons, which would be about 33 mpg in US terms.
The difference also explains why a US gallon holds 128 fluid ounces while a UK gallon holds 160.
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