Volume Converter

What is volume?

Volume measures how much three-dimensional space something occupies, or how much a container can hold. A box has a volume you can get by multiplying its three edges; a bottle has a capacity you read off its label. The two ideas are the same quantity, and the same units serve for both.

In the SI system the base unit is the cubic meter (m³). It is large for daily life, so smaller units are used for most tasks: the liter for drinks and fuel, the milliliter for medicine and recipes, and a long list of customary units in the United States and the former British Empire. This converter moves between all of them.

Metric volume units

Metric volume units follow the powers of ten, with a liter defined as exactly one cubic decimeter. That ties the cubic units and the liter family together neatly.

Cubic inches, feet, yards and miles are measured with cubes built on the length units of the same name. A cubic foot is 0.3048³ m³ = 0.028316846592 m³, which is 28.316846592 L.

US customary and imperial units

The names are the same on both sides of the Atlantic, but the sizes are not. The US liquid gallon is defined as 231 cubic inches, which is exactly 3.785411784 L. The imperial gallon, used in the UK before metrication and still found on some products, is 4.54609 L, about 20% larger.

Subdivisions differ as well. A US gallon holds 4 quarts, 8 pints or 128 fluid ounces. An imperial gallon holds 4 quarts and 8 pints too, but 160 fluid ounces, because the imperial pint is 20 ounces rather than 16. The imperial fluid ounce is therefore slightly smaller (28.41 mL) than the US one (29.57 mL), even though the imperial pint is bigger.

Cups need extra care. The converter offers a US legal cup of 240 mL, the figure used for nutrition labels, and an imperial cup of 10 imperial fluid ounces (284.13 mL). A traditional US kitchen cup of 8 fluid ounces is slightly smaller than the legal one at 236.59 mL, and metric recipes in some countries use a 250 mL cup. If a recipe is precise, check which cup it means. The cooking pages, such as cups to milliliters, go into more detail.

How to convert between volume units

1. Type the amount you have in the first box.
2. Choose its unit in the list next to it.
3. Choose the target unit in the second row. The result updates immediately and keeps up to ten decimal places, with thousands separators for big numbers.

result = amount × (size of source unit in m³) ÷ (size of target unit in m³)The converter does exactly this, taking the cubic meter as its midpoint.

When doing it by hand, find a single factor between the two units, such as 1 US gallon = 3.785411784 L, and multiply or divide. Stay within one system where you can, because the straight metric relationships are exact powers of ten.

Volume conversion examples

Four typical conversions, each worked out with the factors given on this page.

Quick reference table

Limits and good practice

• Volume is not weight. A liter of water weighs about 1 kg, but a liter of flour or honey does not. Going from milliliters to grams needs a density, which is what the density calculator or the cooking converters such as grams to milliliters are for.
• Name the system. "Gallon", "pint" and "ounce" mean different things in the US and the UK, so always pick the US or Imperial option on purpose.
• Dry versus liquid. The US also has dry gallons, pints and quarts for grain and produce. This converter uses the liquid versions only.
• Rounding. Answers are rounded to ten decimals; the imperial spoon sizes rest on a rounded constant of 56,312.104 tablespoons per cubic meter, so they can differ from the textbook definitions in the seventh significant figure.

To work out the volume of a shape in the first place, use the volume calculator, the pool volume calculator or the tank volume calculator, then bring the answer here. For floor and land measurements, the area converter is the matching tool.