Direct comparison
What is the difference between US and imperial gallons?
A US liquid gallon equals 3.785411784 liters, while an imperial gallon equals 4.54609 liters. The imperial gallon is approximately 20% larger.
US gallons are commonly used in the United States. Imperial gallons may appear in older British, Canadian, Caribbean, and Commonwealth specifications or measurements.
The two units must not be used interchangeably for fuel tanks, fuel economy, aquariums, water storage, containers, beverages, or equipment capacities.
This converter produces US liquid gallons rather than imperial gallons.
Unit comparison
US and imperial gallons at a glance
| Feature | US liquid gallon | Imperial gallon |
|---|---|---|
| Liters | 3.785411784 L | 4.54609 L |
| Relative size | Smaller | Larger |
| Common abbreviation | US gal | imp gal |
| Fluid ounces per gallon | 128 US fl oz | 160 imperial fl oz |
| Primary modern use | United States | Limited regional and historical use |
Gallon standards
What is a US liquid gallon?
A US liquid gallon is defined as exactly 231 cubic inches. It equals 4 US liquid quarts, 8 US liquid pints, 16 US customary cups, or 128 US fluid ounces.
Exact liter equivalent
US liquid subdivisions
US fluid-ounce equivalent
What is an imperial gallon?
An imperial gallon equals exactly 4.54609 liters. It contains 4 imperial quarts, 8 imperial pints, or 160 imperial fluid ounces.
Exact liter equivalent
Imperial subdivisions
Imperial fluid-ounce equivalent
Relative capacity
Which gallon is larger?
The imperial gallon is larger than the US liquid gallon. One imperial gallon equals approximately 1.20095 US gallons.
An imperial gallon is about 20.095% larger.
A US gallon is approximately 83.27% of an imperial gallon.
The liter difference between the units is approximately 0.760678216 liter per gallon.
Changing gallon standards
US-gallon and imperial-gallon formulas
The imperial result is numerically smaller because the imperial gallon is larger.
The US result is numerically larger because the US gallon is smaller.
Convert 10 US gallons to imperial gallons
Convert 10 imperial gallons to US gallons
Gallon comparison values
US and imperial gallon conversion table
| US gallons | Imperial gallons | Liters |
|---|---|---|
| 1 US gal | 0.832674 imp gal | 3.785412 L |
| 2 US gal | 1.665348 imp gal | 7.570824 L |
| 5 US gal | 4.163371 imp gal | 18.927059 L |
| 10 US gal | 8.326743 imp gal | 37.854118 L |
| 20 US gal | 16.653486 imp gal | 75.708236 L |
| 50 US gal | 41.633715 imp gal | 189.270589 L |
| 100 US gal | 83.267429 imp gal | 378.541178 L |
Imperial gallons converted to US gallons
| Imperial gallons | US gallons | Liters |
|---|---|---|
| 1 imp gal | 1.200950 US gal | 4.54609 L |
| 2 imp gal | 2.401900 US gal | 9.09218 L |
| 5 imp gal | 6.004751 US gal | 22.73045 L |
| 10 imp gal | 12.009502 US gal | 45.46090 L |
| 20 imp gal | 24.019004 US gal | 90.92180 L |
| 50 imp gal | 60.047510 US gal | 227.30450 L |
| 100 imp gal | 120.095020 US gal | 454.60900 L |
Vehicles and efficiency
Why gallon type matters for fuel
Vehicle fuel tanks, fuel prices, and fuel-economy figures may use different gallon standards. A vehicle described as achieving the same numerical miles-per-gallon value under each standard would not have the same efficiency.
US tank volume
Larger tank volume
For the same numerical gallon value
Miles per gallon, liters per 100 kilometers, and other efficiency units also involve distance and reciprocal calculations.
Tank-capacity labels
US and imperial gallons for tanks and aquariums
Tank capacities described only as gallons can be ambiguous. An imperial-gallon tank holds more liquid than a US-gallon tank with the same numerical capacity.
| Label | If US gallons | If imperial gallons |
|---|---|---|
| 10 gallons | 37.8541 L | 45.4609 L |
| 20 gallons | 75.7082 L | 90.9218 L |
| 50 gallons | 189.2706 L | 227.3045 L |
| 100 gallons | 378.5412 L | 454.6090 L |
Equipment ratings, treatments, filters, pumps, and heaters should use the same gallon standard as the tank-volume calculation.
Reading specifications
How to identify which gallon is being used
- Look for “US gal,” “US gallon,” or “US liquid gallon.”
- Look for “imp gal” or “imperial gallon.”
- Check the country and intended market of the product.
- Compare any listed liter equivalent.
- Review the manufacturer's technical documentation.
- Do not rely on the word “gallon” alone when precision matters.
Converting both capacities to liters can make differences between gallon standards easier to see.
Third gallon unit
What is the US dry gallon?
The US dry gallon is a separate dry-volume unit. It is not the same as either the US liquid gallon or the imperial gallon.
It may appear in agricultural or dry-commodity contexts but should not be used for liquid fuel, water, beverages, aquarium capacity, or ordinary liquid-volume conversion.
3.785411784 liters
4.54609 liters
Different definition
Accuracy check
Common gallon-conversion mistakes
Assuming all gallons are identical
US liquid and imperial gallons differ by approximately 20%.
Using US subdivisions with imperial gallons
US and imperial fluid ounces, pints, and gallons use different definitions.
Comparing fuel economy without checking the gallon
A numerical miles-per-gallon figure changes meaning when the gallon standard changes.
Ignoring the listed liter equivalent
A liter value can reveal which gallon definition a specification uses.
Continue reading
Related liters-to-US-gallons guides
Questions and answers
Frequently asked questions
Which is larger, a US gallon or an imperial gallon?
An imperial gallon is larger and equals approximately 1.20095 US gallons.
How many liters are in a US gallon?
One US liquid gallon equals exactly 3.785411784 liters.
How many liters are in an imperial gallon?
One imperial gallon equals exactly 4.54609 liters.
Can US and imperial gallons be used interchangeably?
No. They have different volumes and produce different fuel, tank, and equipment calculations.
Convert a volume
Use the Liters to US Gallons Converter
Enter any positive whole or decimal liter measurement to calculate US liquid gallons instantly.
Open Liters to US Gallons ConverterLast updated: July 27, 2026