🪣 Gallon Calculator
Convert a volume in gallons to liters, quarts, pints, cups, and fluid ounces, using either US or UK gallon definitions.
US vs. UK gallons
A US gallon and a UK (imperial) gallon are not the same size. A US gallon equals 3.785 liters, while a UK gallon equals 4.546 liters — about 20% larger. This calculator lets you pick the correct definition for your region before converting.
How this calculator works
Enter the number of gallons and select US or UK. The calculator multiplies your value by the correct liters-per-gallon constant, then derives quarts, pints, cups, and fluid ounces using the standard subdivisions within each gallon system (4 quarts, 8 pints, 16 cups per gallon in both systems, though the absolute size of each unit differs between US and UK).
- 1 US gallon = 3.785 liters = 128 fl oz (US)
- 1 UK gallon = 4.546 liters = 160 fl oz (UK)
Always confirm which gallon standard a recipe, fuel economy figure, or product label is using, especially when working across US and UK/international sources.