A US gallon and an imperial gallon share a name but differ by about 20 percent, and a cup isn't the same size in every country either. This converter handles litres, millilitres, cubic metres, gallons, quarts, pints, cups, fluid ounces, tablespoons, teaspoons and cubic feet and inches, and lays every result out together so you can pick the one you need.
How to use it
- Type the amount you have.
- Choose the unit you're converting from and to.
- Read the headline result and scan the table of other units.
- Swap units if you need the reverse.
When it helps
- Converting recipes between metric measures and US cups and spoons.
- Working out how much liquid a tank, pool or aquarium holds.
- Comparing fuel or drink sizes between US and UK listings.
- Checking container sizes on shipping or import paperwork.
Good to know
- Gallons, quarts, pints, cups and fluid ounces are US measures unless the label says imperial.
- A US gallon is about 3.785 litres; an imperial gallon is about 4.546 litres.
- If your recipe goes between volume and weight, use the Cooking Measurement Converter instead, because ingredients weigh different amounts per cup.
How the conversion works
All volumes are converted through litres. A millilitre is a thousandth of a litre, a cubic metre is 1,000 litres, and the US units are defined from the gallon: 3.785411784 litres, split into four quarts, eight pints, sixteen cups and 128 fluid ounces. The imperial gallon is different, at 4.54609 litres, with 160 fluid ounces.
That is why the same word can mean two different amounts. An American pint is 16 US fluid ounces, about 473 ml, while a British pint is 20 imperial fluid ounces, about 568 ml. The tool labels each unit so you always know which you're using.
Worked example: a fish tank
A tank measures 60 cm by 30 cm by 35 cm. Multiply to get 63,000 cubic centimetres, enter that with cm³ selected, and the table shows 63 litres, or about 16.6 US gallons. That figure matters because filters and treatments are rated by volume, and most are labelled in gallons or litres, depending on where they are sold.
A pool is similar on a bigger scale. A 5 by 3 metre pool filled to 1.2 metres holds 18 cubic metres, or 18,000 litres, which is roughly 4,755 US gallons. Converting before you buy chemicals avoids a costly dosing mistake.
Mistakes people make
The biggest is mixing US and imperial measures. A recipe from a British book that says 1 pint of milk means 568 ml, not 473. Another is confusing fluid ounces, which measure volume, with ounces, which measure weight. A fluid ounce of water weighs about one ounce, but a fluid ounce of honey weighs considerably more.
Also watch teaspoons and tablespoons. The US tablespoon is about 14.8 ml, the metric one used in Australia is 20 ml, and the UK and most of the world use 15 ml. For baking, small differences matter, so check which standard a recipe uses.
Everyday reference points
A teaspoon is about 5 ml, a tablespoon about 15, a US cup about 237, and a litre is a little more than a US quart. A standard can of drink is 330 ml, a wine bottle 750 ml, a bucket around 10 litres, and a bathtub roughly 150 to 200.
A cubic metre is a thousand litres, which is also the volume of one tonne of water. That link between volume and mass makes water the easiest substance to estimate with.
Questions
How many litres in a US gallon?
3.785.
Is a UK pint the same as a US pint?
No. The imperial pint is about 568 ml and the US pint about 473 ml.