Volume converter

How many liters are in a gallon?

One US liquid gallon is exactly 3.785411784 liters and one imperial (UK) gallon exactly 4.54609 liters, about 20% more. Which gallon you need depends on the source: American fuel, milk and containers use the US gallon, British figures the imperial one.

Where the exact values come from

The US gallon is defined as 231 cubic inches. With the inch fixed at 2.54 cm, that is 231 × 2.54³ = 3,785.411784 cm³, or 3.785411784 L (NIST Handbook 44).

The imperial gallon is set directly in metric units: the UK Weights and Measures Act 1985 defines it as 4.54609 L. One imperial gallon is therefore 1.20095 US gallons.

The liter itself is one cubic decimeter, 0.001 m³, and a milliliter is one cubic centimeter, which is why cc and mL mean the same volume (BIPM SI Brochure).

Every unit in liters

Liter and litre are two spellings of the same unit, symbol L. Each row is the number of liters in one of that unit.

The rows follow these conventions:

• US units are liquid measures. US dry pints and quarts, used for berries and other produce, are larger units.
• The metric cup is 250 mL, as in Australia, New Zealand and Canada. US nutrition labels use a 240 mL cup (21 CFR 101.9), and Australian recipes use a 20 mL tablespoon; convert those from milliliters.
• The oil barrel is 42 US gallons. A US beer barrel is 31 gallons, so check which barrel a source means.
• The acre-foot is 43,560 cubic feet, an acre covered one foot deep, measured in international feet. Older US records may use the slightly longer survey foot (NIST).

US and imperial measures differ at every size

An imperial pint is 20 imperial fluid ounces, 568.26 mL. A US pint is 16 US fluid ounces, 473.18 mL. A British pint of milk or beer is therefore about 20% larger than an American one.

The fluid ounces run the other way: the imperial ounce, 28.41 mL, is smaller than the US ounce, 29.57 mL. NIST's conversion tables list the two systems as separate units.

Cubic units scale by the cube

A yard is 3 feet, but a cubic yard is 3 × 3 × 3 = 27 cubic feet, or 764.55 L. Likewise a cubic foot is 1,728 cubic inches, not 12.

• 1 ft³ = 28.32 L = 7.48 US gallons, a common figure for pools and tanks.
• 1 m³ = 1,000 L = 264.17 US gallons.

To get a volume from measurements, multiply length, width and depth in one unit before converting. A 12 × 15 ft room with an 8 ft ceiling holds 1,440 ft³, or 40.78 m³. The solid volume calculator handles cylinders, spheres and other shapes.

Volume is not weight

A liter of water weighs about 1 kg, 998.2 g at 20 °C, but a liter of oil or honey does not. To go between liters and kilograms you need the liquid's density; the density converter puts it in matching units.

Fluid ounces measure volume, while ounces on a scale measure mass. Convert the second kind with the weight converter, and kitchen ingredients with the cooking converter.