How to use the Volume Converter
- Enter the volume figure you have.
- Select the source unit, checking carefully whether it is US or imperial.
- Select the target unit.
- Use cubic metres or cubic feet when working with tanks, rooms or freight rather than liquids.
- For baking by weight, use the cooking converter, which accounts for ingredient density.
How the calculation works
Every unit converts through the litre, defined since 1964 as exactly one cubic decimetre, or 0.001 cubic metres. This makes metric volume conversions exact and ties them directly to the length units, which is why one cubic centimetre and one millilitre are the same thing.
The US and imperial systems diverged in 1824 when Britain redefined the gallon as the volume of ten pounds of water, giving 4.54609 litres. The US retained the older Queen Anne wine gallon of 231 cubic inches, or 3.785 litres. The imperial gallon is therefore about 20% larger, and every derived unit inherits the gap: an imperial pint is 568 ml against the US 473 ml, and an imperial fluid ounce is slightly smaller than the US one despite the larger parent unit, because the imperial gallon divides into 160 fluid ounces rather than 128.
That 20% gap is the reason fuel-economy figures need care. A car rated at 40 imperial MPG is only about 33 US MPG for identical real-world consumption. Nothing about the vehicle changed; only the size of the gallon did. Any comparison of consumption figures across the Atlantic must state which gallon is in play or it is meaningless.
volume_target = (volume_source × L_per_source) ÷ L_per_target; 1 L = 1 dm³ exactly; US gal = 3.785411784 L; imperial gal = 4.54609 LSource: 12th CGPM (1964) definition of the litre; NIST Handbook 44 Appendix C; UK Weights and Measures Act 1985.
Worked example
A British recipe calls for 1.5 imperial pints of stock and you only have US measuring cups.
- Enter 1.5 and select imperial pints.
- Convert to litres: 1.5 × 0.56826 = 0.8524 L.
- Convert litres to US cups: 0.8524 ÷ 0.236588 = 3.60 cups.
- Measure 3 cups plus a further 9.6 tablespoons, or simply use 852 ml on a scale.
1.5 imperial pints is 852 ml, or 3.6 US cups — noticeably more than the 3 cups a straight pint-for-pint substitution would have given.
Frequently asked questions
Is a US pint the same as a UK pint?+
No. A US pint is 473 ml, an imperial pint is 568 ml — a 20% difference that matters in any recipe or bar measure.
How many millilitres in a cup?+
A US legal cup is 240 ml, the US customary cup used in recipes is 236.6 ml, and a metric cup is 250 ml. This calculator uses the customary 236.6 ml.
Are dry and liquid measures the same?+
For US volume units, dry pints and quarts are separate, larger units. Liquid measures are what this converter uses, which is what almost all recipes intend.
How do I get volume from dimensions?+
Multiply length by width by height in consistent units, then convert. A tank 2 m × 1 m × 0.5 m holds 1 m³, which is 1,000 litres.
Last reviewed September 1, 2026. We review this page whenever the underlying formula, tax year, published rate or standard changes.