US and UK gallons aren’t the same size, and gallons themselves convert to a wide range of other volume units depending on context. This calculator handles both gallon types and converts to eight different target units, plus shows the equivalent water weight.

How to use this gallon calculator

1. Choose your Gallon Type: US Gallon or Imperial (UK) Gallon.
2. Enter the number of Gallons.
3. Choose what to Convert To: liters, milliliters, cubic meters, cubic feet, US quarts, pints, cups, fluid ounces, or the other gallon type.
4. Read your converted result, plus the equivalent Weight of Water in pounds and kilograms.

What this calculator does

A US gallon (3.78541 L) is meaningfully smaller than an imperial UK gallon (4.54609 L), about 17% smaller, which matters for anything sourced from American versus British/Commonwealth contexts, recipes, fuel economy figures, and container sizes. This calculator defaults to US gallons, the standard in American recipes and fuel pricing, but supports converting either type.

Why the water weight figure is included

Alongside the volume conversion, this calculator shows what that volume of water would weigh, 8.34 lb per US gallon, or 10.02 lb per UK gallon, at standard temperature. This is useful context for anything involving tank capacity, shipping weight, or load calculations where you need to reason about weight as well as volume.

Frequently asked questions