Convert gallons to liters, quarts, pints, cups, and more. Supports both US and Imperial gallons for international conversions.
Last updated: March 2026 | By Patchworkr Team
A gallon is a unit of volume measurement used primarily in the United States and some other countries. There are two different gallon definitions in use: the US gallon and the Imperial (UK) gallon.
The US gallon is defined as exactly 231 cubic inches, which equals approximately 3.785411784 liters. The Imperial gallon is exactly 4.54609 liters.
This difference is important in international trade and travel. A British gallon of fuel is about 20% larger than an American gallon, which can lead to confusion when comparing fuel economy between countries.
A US gallon is 3.785411784 liters while an Imperial gallon is 4.54609 liters. The Imperial gallon is about 20% larger.
A US gallon contains 3.785411784 liters. An Imperial gallon contains 4.54609 liters.
There are 16 US cups in a US gallon.
The US and Imperial gallons diverged historically. The Imperial gallon was standardized in 1824, while the US retained its earlier definition.
One US gallon equals 128 US fluid ounces. Multiply US gallons by 128 to get US fluid ounces.
The US primarily uses US gallons. Some countries historically used Imperial gallons, though liters are now more common internationally.
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