Volume Converter
Litres, cubic metres and millilitres
The metric system ties volume to length: 1 litre = 1 dm³, 1 mL = 1 cm³ and 1 m³ = 1,000 L. A 1 m × 1 m × 1 m tank holds 1,000 litres.
US vs UK gallons
The biggest trap in volume conversion is that the US and the UK use different gallons:
| Unit | In litres |
|---|---|
| 1 US gallon (231 in³) | 3.785 L |
| 1 UK (imperial) gallon | 4.546 L |
| 1 US quart = ¼ US gal | 0.946 L |
| 1 US pint = ½ US quart | 0.473 L |
| 1 US cup = ½ US pint | 236.6 mL |
| 1 US fluid ounce | 29.57 mL |
A UK gallon is about 20% larger than a US gallon, so fuel economy figures in miles per gallon are not comparable between the two countries.
Cooking measures
- 1 US tablespoon = 14.79 mL and 1 US teaspoon = 4.93 mL. Metric spoons are rounded to 15 mL and 5 mL — the difference does not matter in a recipe.
- 1 US cup = 16 tablespoons = 48 teaspoons. US nutrition labels use a rounded "legal cup" of 240 mL.
- Cups measure volume, not weight: a cup of flour weighs about 125 g, a cup of sugar about 200 g. Use a kitchen scale for baking precision.
Worked example
A 50-litre fuel tank in US gallons: 50 ÷ 3.785 = 13.21 US gal (or 11.0 UK gallons). To compare fuel consumption, our fuel consumption calculator gives litres per 100 km; you can convert a US mpg figure with L/100 km = 235.21 ÷ mpg.
Frequently Asked Questions
How many litres are in a gallon?
A US gallon is 3.785 litres; a UK (imperial) gallon is 4.546 litres. Check which one your source uses.
How many millilitres are in a cup?
A US cup is 236.6 mL (240 mL on nutrition labels). Metric cups used in Australia and elsewhere are 250 mL.
Is a litre of water one kilogram?
Almost: one litre of pure water weighs about 1 kg at 4 °C. Other liquids differ — a litre of oil weighs about 0.92 kg.