About the Volume Converter

The volume converter translates between metric and imperial units of volume, including millilitres, litres, cubic metres, cubic centimetres, cubic inches, cubic feet, cups, pints, quarts, US gallons, and UK gallons. Whether you are scaling a recipe, measuring a fuel tank, or computing the volume of a shipping container, this tool gives you an instant conversion in either direction.

Volume units are cubed versions of length units, so the conversion factors are the cubes of the corresponding length factors. One cubic metre is not 100 cubic centimetres but one million, because each side of the cube is 100 centimetres and the volume is 100 times 100 times 100. This cubing effect means that volume conversions involve much larger or smaller numbers than the corresponding length conversions.

A common source of confusion is the difference between the US gallon (about 3.785 litres) and the UK imperial gallon (about 4.546 litres). The two differ by about 20%, so a recipe or fuel specification that simply says "gallon" can be ambiguous. This converter handles both explicitly to avoid mistakes.

How It Works

Each unit has a defined relationship to the litre, the most commonly used metric unit of volume. The converter uses these factors to translate between any two units:

1 ml    = 0.001 L
1 L     = 1 L
1 m3    = 1000 L
1 cm3   = 0.001 L          (same as 1 ml)
1 in3   = 0.016387064 L    (exact, 0.0254 cubed)
1 ft3   = 28.316846592 L   (exact, 0.3048 cubed)
1 cup   = 0.2365882365 L   (US legal cup, 8 US fluid ounces)
1 pt    = 0.473176473 L    (US liquid pint, 2 cups)
1 qt    = 0.946352946 L    (US liquid quart, 2 pints)
1 gal   = 3.785411784 L    (US gallon, 4 quarts)
1 galUK = 4.54609 L        (UK imperial gallon)

Every conversion proceeds in two steps: the input is multiplied by the source unit's factor to give a volume in litres, then divided by the target unit's factor to give the result in the target unit. The cubic unit factors are exact cubes of the corresponding length definitions.

The US gallon is defined as exactly 231 cubic inches, which equals approximately 3.785 litres. The UK imperial gallon was defined in 1824 as the volume of ten pounds of water at a specific temperature and pressure, which equals approximately 4.546 litres. The two gallons differ by about 20%, which is why fuel economy figures differ between US and UK sources.

Worked Examples

To convert 1 US gallon to litres, the calculation is 1 * 3.785411784 = 3.785 litres. To convert 1 UK gallon to litres, the calculation is 1 * 4.54609 = 4.546 litres. The difference of about 0.76 litres is why a car's fuel economy looks different when expressed in US mpg versus UK mpg.

To convert 1 cubic foot to litres, the calculation is 1 * 28.316846592 = 28.32 litres. This is the volume of a cube one foot on each side, and it is a common unit for refrigerator and aquarium capacities in the United States.

To convert 2 cups to millilitres, the calculation is 2 * 0.2365882365 * 1000 = 473.18 ml. This is a common cooking conversion, since recipes often call for cups in the US and millilitres in most of the rest of the world.

When to Use This Tool

Use the volume converter whenever you need to translate between volume units:

Scaling recipes that use cups, pints, or quarts versus millilitres or litres.
Converting fuel tank capacities between gallons and litres.
Computing the volume of shipping containers or storage spaces.
Interpreting beverage sizes from another country (US vs UK pints and gallons).
Working with aquarium or pool volumes measured in different units.
Converting engine displacements between cubic inches, cubic centimetres, and litres.
Teaching the relationships between metric and imperial volume units.

Limitations & Disclaimer

This converter handles US liquid volume units and the UK imperial gallon. It does not convert US dry measure (dry pint, dry quart, peck, bushel) or historical units. Cooking conversions use the US legal cup; Australian and metric cups differ slightly. For pharmaceutical or laboratory work, use calibrated measuring instruments. See our disclaimer for full details.

Frequently Asked Questions

What is the difference between a US gallon and a UK gallon?

The US gallon is approximately 3.785 litres, defined as 231 cubic inches. The UK imperial gallon is approximately 4.546 litres, defined as the volume of ten pounds of water. The two differ by about 20%, which is why fuel economy figures and beverage sizes differ between the two countries.

Why is 1 cubic metre equal to 1000 litres, not 100?

Because volume is length times width times height, and all three dimensions scale. A cubic metre is 100 centimetres on each side, so its volume is 100 times 100 times 100, which is one million cubic centimetres. Since one cubic centimetre equals one millilitre, a cubic metre equals one million millilitres or 1000 litres.

Is a cubic centimetre the same as a millilitre?

Yes, exactly. One cubic centimetre (cm3 or cc) equals one millilitre (ml) by definition. The two units are interchangeable, though millilitre is more common in everyday use and cubic centimetre is more common in engineering and medical contexts.

What is a US cup and how does it relate to other units?

A US cup is 8 US fluid ounces, approximately 236.6 millilitres or 0.2366 litres. It is half a US liquid pint, a quarter of a US quart, and one-sixteenth of a US gallon. The US legal cup is slightly different at exactly 240 millilitres, used for nutrition labelling.

Why are there different pint sizes?

The US liquid pint is approximately 473 millilitres, while the UK imperial pint is approximately 568 millilitres. The two differ by about 20%, matching the difference between the US and UK gallons. A pint of beer in the United States is smaller than a pint in the United Kingdom.

How accurate are the conversions?

The metric-to-metric conversions are exact. The imperial-to-metric conversions are exact by the 1959 international agreement on the inch. The only source of error is floating-point rounding, which is negligible for any practical purpose. The converter displays up to eight decimal places for precision.

Last updated: July 21, 2026 · Author: HT99 Tools Editorial Team · Reviewed by: HT99 Tools Editorial Team