Unit converter
US Gallons to Liters Converter
This tool changes US gallons into litres. By definition one US gallon is exactly 3.785411784 litres, a value that traces back to 231 cubic inches. The conversion helps when filling a car abroad where pumps read in litres, scaling an American recipe to a metric measuring jug, working out the litre capacity of a tank or drum quoted in gallons, or buying paint and chemicals sold by the US gallon. Type the gallon figure and the litre total appears straight away, with a short table of the amounts looked up most often.
1 US gallon = 3.7854 liters
Common US gallons to liters values
| US gallons | Liters |
|---|---|
| 1 gal | 3.7854 l |
| 2 gal | 7.5708 l |
| 5 gal | 18.9271 l |
| 10 gal | 37.8541 l |
| 20 gal | 75.7082 l |
| 50 gal | 189.27 l |
| 100 gal | 378.54 l |
How to convert
- Start with the volume in US gallons.
- Multiply by 3.785411784 to get litres, the exact number of litres in one US gallon.
- For everyday work the rounded factor 3.785 is close enough.
- Reverse the conversion by dividing litres by 3.785411784 to recover US gallons.
- A quick estimate: each US gallon is just under four litres, so multiply by roughly 3.8.
litres = US gallons × 3.785411784
A US gallon is 231 cubic inches, which works out to exactly 3.785411784 litres. Multiplying a gallon figure by this constant gives litres; dividing litres by it returns US gallons. The factor is exact, so the only rounding is whatever precision you choose to display.
- gal
- the volume in US gallons you start with
- 3.785411784
- litres in one US gallon, by definition
Worked example
A 5 US gallon water container is 5 times 3.785411784, which is about 18.93 litres. A single US gallon of milk holds close to 3.79 litres, nearly a four-litre carton.
Key facts
- One US gallon is exactly 3.785411784 litres.
- A US gallon equals 231 cubic inches.
- Ten US gallons come to about 37.85 litres.
- The US gallon is smaller than the 4.54609 litre imperial gallon.
Tips
- Multiplying by 3.8 gives a quick litre estimate that is close for most everyday volumes.
- For tank or drum sizing, convert the full gallon figure once and label the container in litres to avoid repeat sums.
Frequently asked questions
How many litres in 1 US gallon?+
Exactly 3.785411784 litres.
How many US gallons make a litre?+
About 0.264172, so one litre is just over a quarter of a US gallon.
Why does my US gallon differ from a UK gallon in litres?+
The imperial gallon is bigger, at 4.54609 litres. A US gallon is the smaller of the two, so always confirm which gallon a figure uses.
How big is a US gallon of fuel in litres?+
Just under 3.79 litres, which is why a 15 US gallon tank holds roughly 56.8 litres.
Things to watch
- Check whether a source means US or imperial gallons; using the wrong one skews the litre result by about 20 percent.
- Volume changes slightly with temperature for fuels, so a tank rated in gallons may not deliver the exact litre figure when warm.
Sources
Last updated: 2026-01-01
Conversions use internationally defined factors. Provided for general use; verify critical measurements independently.