What a gallon is and why there are two
The liter is the metric unit of volume, and the gallon is its counterpart in the English-speaking world. Converting between them looks simple, but there’s a catch: there isn’t one gallon, there are two, and both are still in daily use.
The US gallon equals 3.785411784 liters, while the imperial gallon (UK), used in the United Kingdom and parts of the Commonwealth, equals 4.54609 liters. That makes the imperial gallon roughly 20% larger than the US one (put the other way, a US gallon is about 17% smaller than an imperial one). Mixing them up when buying fuel or reading a recipe can throw your numbers off noticeably, so this converter includes a selector to keep you on the right one.
How to use the converter
- Pick the gallon type you need: US or imperial (UK). It defaults to US, the one used across the Americas.
- Type a value in liters to get gallons instantly.
- Or type a value in gallons to get liters — the conversion runs both ways.
- Check the secondary card to see what the same amount would be in the other gallon type.
- Hit Copy to grab the result wherever you need it.
The formula
Converting is a simple division or multiplication by the factor of the chosen gallon:
- US gallons = liters ÷ 3.785411784
- Imperial gallons = liters ÷ 4.54609
- Liters = gallons × 3.785411784 (US) or × 4.54609 (imperial)
Worked example
Say you put 10 liters of gasoline in your car and want to know how many gallons that is. Using the US gallon:
10 ÷ 3.785411784 = 2.642 US gallons
With the imperial gallon, the same amount would be 10 ÷ 4.54609 = 2.200 UK gallons. Going the other way, 5 US gallons of water are 5 × 3.785411784 = 18.927 liters. The gap between the two gallons is real, which is why it pays to know which one you’re using.
Conversion table
| Liters | US gallons | Imperial gallons |
|---|---|---|
| 1 L | 0.264 | 0.220 |
| 5 L | 1.321 | 1.100 |
| 10 L | 2.642 | 2.200 |
| 20 L | 5.283 | 4.399 |
| 40 L | 10.567 | 8.799 |
| 50 L | 13.209 | 10.998 |
| 100 L | 26.417 | 21.997 |
Frequently asked questions
How many liters are in a gallon?
It depends on the gallon. A US gallon holds 3.785411784 liters (3.785 L rounded), and a British imperial gallon holds 4.54609 liters (4.546 L). When people say “a gallon” without context in the Americas, they almost always mean the US one.
What’s the difference between US and imperial (UK) gallons?
The imperial gallon is bigger: it holds about 0.76 liters more than the US gallon, roughly a 20% difference. They come from separate historical measuring systems that were never unified. That’s why a car’s “miles per gallon” figure can’t be compared between the US and the UK without converting first.
How many gallons is a tank of X liters?
Divide the tank’s liters by 3.785411784 for US gallons. A 40-liter tank is 10.567 US gallons; a 50-liter tank is 13.209 US gallons; and a 60-liter tank is 15.850 US gallons. Type your exact capacity into the converter for your own case.
Which gallon should I use in the US or Latin America?
The US gallon. Like much of Latin America, countries such as the Dominican Republic sell fuel, water and paint using the 3.785-liter US gallon. If you see a price “per gallon” there, it’s almost certainly the US gallon, so leave the converter on the US option.