Volume Converter
Convert litres, millilitres, cubic metres, gallons, quarts, pints and cups.
The volume converter converts between metric and US customary units of capacity. Use it for cooking, fuel, tank sizes, beverages and shipping volumes. Note that US and UK gallons differ, so check which one a recipe or product uses.
How to use the converter
- Enter the volume to convert.
- Pick the from and to units.
- Read the result and the full conversion table.
- Remember the table uses US gallons, not imperial.
How the conversion works
Result = value in litres ÷ factor of the target unit
Worked example
5 litres to US gallons
5 L ÷ 3.785411784 = 1.321 US gallons
The same volume is 5,000 ml or about 21.13 US cups.
Popular conversions
Jump straight to a single conversion, or use the converter above for any pair.
Who should use this volume converter
- Cooks working from recipes that use cups, pints or fluid ounces while the kitchen measures in millilitres.
- Drivers and travellers comparing fuel tank sizes or fuel economy figures quoted in gallons.
- Anyone sizing a water tank, an aquarium, a fuel can or a container where the capacity is stated in another unit.
- Shipping and packaging work, where liquid volumes must be declared accurately.
Common mistakes to avoid
- Mixing up US and UK gallons. A US gallon is 3.785 litres and an imperial gallon is 4.546 litres — about 20% larger. Fuel economy figures and tank sizes change meaning entirely with the wrong one.
- Treating a fluid ounce as a weight. Fluid ounces measure volume. An ounce of honey weighs more than a fluid ounce of honey because honey is denser than water.
- Assuming one litre equals one kilogram. That is only true for water near 4°C. Oil floats, so a litre weighs less; honey sinks, so it weighs more.
- Ignoring cup size differences. A US cup is 236.6 ml and a metric cup is 250 ml. Over four or five cups in a recipe, that adds up to a noticeable difference.
- Confusing millilitres with cubic centimetres. They are identical, so no conversion is needed — many people convert them unnecessarily and introduce rounding errors.
Why US and UK gallons disagree
The gallon predates standardisation and was defined differently on each side of the Atlantic. The US kept an older wine gallon, the UK later settled on a larger imperial gallon. The 20% gap survives in everyday use: a car returning 50 miles per US gallon is doing about 60 miles per imperial gallon, which is why fuel economy comparisons between countries need converting first.
Volume also depends on temperature, though only slightly for everyday purposes. Water expands as it warms, so a litre at 80°C takes up slightly more space than a litre at 4°C. For cooking, fuel and shipping, that effect is negligible. For laboratory or industrial work it is not, which is why precision measurements specify the temperature at which the volume was measured.
Volume units explained
- Litre
- One thousand millilitres, or one cubic decimetre. The standard unit for liquids in most countries.
- US gallon
- 3.785411784 litres. Used for fuel and liquids in the United States.
- Imperial gallon
- 4.54609 litres, about 20% larger than the US gallon.
- Fluid ounce
- A unit of volume, not weight. The US fluid ounce is 29.57 ml; the imperial one is 28.41 ml.
- Cubic metre
- 1,000 litres. Used for water supply, gas and bulk materials.
Cooking conversions that matter
Kitchen measures vary more than people expect. A US cup holds 236.6 ml while a metric cup is 250 ml, a US tablespoon is 14.8 ml against a metric 15 ml, and a teaspoon is about 5 ml in both. A US fluid ounce is 29.6 ml and an imperial one is 28.4 ml — close enough for a drink, not for a recipe scaled up five times.
Where the difference really bites is with dense ingredients. A cup measures volume, and the same cup of flour, sugar or honey weighs three very different amounts. If a recipe gives weights, use a scale. If it gives cups, convert to millilitres and treat the result as approximate rather than exact.
Frequently asked questions
How many litres are in a US gallon?
One US gallon is about 3.785 litres. A UK imperial gallon is larger, at about 4.546 litres, so always check which gallon a label refers to.
How many millilitres are in a cup?
A US cup is about 236.6 ml. In cooking, a metric cup is often rounded to 250 ml, which is why recipe results can vary slightly.
How do I convert litres to cubic metres?
Divide litres by 1,000. So 2,500 litres is 2.5 cubic metres, since one cubic metre holds exactly 1,000 litres.