Volume Unit Converter
Convert volume between litres, millilitres, cubic metres and US liquid units — cups, pints, quarts and gallons.
How it works
litres = value × factor(from) · result = litres ÷ factor(to) (1 US gallon = 3.785411784 L)
Volumes convert through the litre. US liquid measures build up from the gallon (3.785411784 L): a quart is a quarter gallon, a pint an eighth, a cup a sixteenth, and a US fluid ounce is 1/128 of a gallon. Imperial (UK) gallons are about 20% larger at 4.54609 L, so US and imperial pints, quarts and gallons are not interchangeable.
Worked example
Convert 1 US gallon to litres: 1 × 3.785411784 = 3.785411784 L, close to 3.79 L. That same gallon is 4 US quarts or 128 US fluid ounces.
Frequently asked questions
How many litres are in a US gallon?
Exactly 3.785411784 litres. An imperial (UK) gallon is larger at 4.54609 litres, so be sure which gallon a recipe or fuel figure refers to.
Is a US cup the same as a metric cup?
No. A US customary cup is about 236.6 mL, while a metric cup is exactly 250 mL. The difference is small but matters in baking, where volume ratios count.
Why do US and UK fluid ounces differ?
A US fluid ounce is about 29.57 mL, while a UK (imperial) fluid ounce is about 28.41 mL. They come from different gallon definitions, so they never quite match.
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This calculator is for educational purposes. Double-check important results before acting on them.