Volume Converter

Volume measures how much space a substance occupies. This converter handles cubic metres, litres and millilitres alongside US and imperial gallons, quarts, pints, cups and fluid ounces, essential for cooking, fuel, chemistry and engineering.

Because US and imperial measures of the same name differ in size, this tool keeps them separate so your conversions stay accurate.

The word "gallon" refers to two different quantities depending on which side of the Atlantic it is used, and the difference is large enough to ruin a calculation rather than merely blur it. A US gallon is 3.785 litres. An Imperial gallon, still used in the UK and some Commonwealth countries, is 4.546 litres.

That makes the Imperial gallon 20.1% larger than the US gallon. Converting a fuel figure, a tank capacity or a chemical volume with the wrong one introduces a fifth of the total as error, in whichever direction the mistake was made.

• The same split runs through the smaller units. An Imperial pint is 568 mL against a US pint of 473 mL, again 20.1% larger.
• Fluid ounces diverge in the opposite direction: an Imperial fluid ounce is slightly smaller than a US one, because the Imperial pint contains 20 of them and the US pint contains 16.
• This converter lists US and Imperial units separately for exactly this reason. Selecting the right one matters more than the arithmetic that follows.

Fuel economy is where this bites most often. A car rated at 40 miles per Imperial gallon manages only about 33 miles per US gallon: the same car, the same efficiency, two very different-looking numbers.

Volume units come in two families that share names but not sizes. Liquid measures and dry measures are separate systems in US customary units, so a dry pint and a liquid pint describe different amounts of space.

Recipes and agricultural measures are where the two collide. Dry commodities are traditionally sold by dry volume (pecks and bushels) while cooking uses liquid measures throughout, even for solids like flour.

• A US dry pint is roughly 16% larger than a US liquid pint.
• Bushels and pecks belong to the dry system and have no direct liquid equivalent. This site keeps them on a separate dry-volume converter.
• Weighing is more reliable than measuring by volume for dry ingredients, because the same cup of flour can vary substantially in mass depending on how it was filled.