Volume Converter

Volume Unit Converter Online

Enter a number, choose the unit you have in the From list and the unit you want in the To list, and read the converted figure. The two lists carry the same 30 volume units, from teaspoons and cups up to acre-feet and register tons.

Why volume units cause so much trouble

Volume is the amount of three-dimensional space something takes up. The SI unit is the cubic meter. Outside freight and construction, though, few people reach for it, so the same quantity ends up written in liters, gallons, pints, or fluid ounces depending on where you are and what trade you are in.

That is where the errors creep in, and they are rarely small. Three traps account for most of them.

The US gallon and the UK gallon are not the same size

This is the most common volume mistake in transatlantic work. A US liquid gallon and a UK imperial gallon are different quantities, and the imperial one is the larger of the two. Convert a fuel figure, a recipe, or a shipping quote with the wrong gallon and the answer is out by roughly a fifth.

The lists carry Gallon (US,liq), Gallon (US,dry) and Gallon (UK) as three separate entries because all three are different sizes. Pick deliberately rather than reaching for whichever gallon appears first.

US dry and liquid measures are different units

US customary measure splits several units into dry and liquid versions, and they are not interchangeable. Pint (US,dry) and Pint (US,liq) are different quantities, and the same split applies to the quart and the gallon. Dry measures turn up in agriculture and bulk goods, liquid measures in cooking and fuel.

Fluid ounces differ by country too

Ounce (US,fluid) and Ounce (UK,fluid) are separate entries because they are separate quantities. The gap is only a few percent, so one ounce either way rarely shows. Scale a British recipe up for a crowd, or batch a drinks order, and it stops being invisible. Pick the country the recipe was written in.

What is in the two lists

Both dropdowns carry the same 30 units. Grouped by the kind of work they show up in:

• Metric: Cubic Meter, Cubic centimeter, Cubic millimeter, Liter (new), Liter (old), Stere
• Cooking and capacity: Cup, Tablespoon, Teaspoon, Fluid ounce (US), Ounce (US,fluid), Ounce (UK,fluid), Gill (US), Gill (UK), Pint (US,liq), Pint (US,dry), Quart (US,liq), Quart (US,dry), Gallon (US,liq), Gallon (US,dry), Gallon (UK)
• Derived from length: Cubic foot, Cubic inch, Cubic yard
• Trade and bulk: Acre-foot, Barrel (oil), Board foot, Bushel (US), Peck (US), Ton (register)

Two entries deserve a note. Liter (old) is the pre-1964 definition of the liter and differs from the modern one by a tiny fraction of a percent, so pick Liter (new) unless you are reproducing historical measurements. The US fluid ounce is also named twice, once as Fluid ounce (US) and once as Ounce (US,fluid), so do not be thrown by seeing it in both forms.

Where these units actually show up

Kitchens. American recipes work in cups and spoons, European ones in milliliters. Anyone cooking across that divide converts constantly, and the habit worth building is checking whether a recipe was written with US or UK ounces before you start measuring.

Shipping and packaging. Freight quotes arrive in cubic feet in the United States and cubic meters almost everywhere else. A warehouse team in Rotterdam quoting a client in Ohio will move between the two several times a day.

Timber. The board foot is a lumber trade unit, and you will not meet it outside the timber yard. If you are pricing timber from a North American supplier it is unavoidable.

Water management. The acre-foot is the standard unit for reservoirs and irrigation allocations in the western United States. It is a large unit and converts poorly in your head.

Fuel and chemicals. The oil barrel is a fixed trade quantity rather than a physical container, which surprises people the first time they convert one.

A note on precision

Converting between unit systems almost always produces a long decimal, because the two systems were never designed to line up. Round the figure yourself at the end of your working, not partway through, and only to the precision your job actually needs. A recipe does not need six decimal places. A laboratory protocol might.

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For a plain English walkthrough of the metric and imperial systems, see our guide to metric and imperial length and distance conversions.