Volume questions come up everywhere: how much water a pool holds, how many liters of fuel fit in a tank, how a European recipe’s deciliters compare with cups, or how much concrete fills a cubic yard. The trouble is that “gallon,” “pint” and “fluid ounce” each mean two different sizes depending on whether you follow US or British measure. This converter keeps them apart and uses exact legal definitions for all 31 units it supports.
How to use the volume converter
- Enter the amount in Value.
- Choose the starting unit in From and the unit you need in To. US units are labeled “US”; British ones are labeled “imperial.”
- The tape shows the result, both conversion factors and the weight of that volume if it were water.
- The table lists the same volume in every unit, so you can compare metric, US liquid, US dry and imperial measures side by side.
Volume conversion formula
Each unit is stored as an exact number of cubic meters, so every conversion follows the same rule:
The anchor definitions are short. A liter is one cubic decimeter (0.001 m³). The US gallon is exactly 231 cubic inches, and since 1 inch is exactly 2.54 cm, that works out to exactly 3.785411784 L. The imperial gallon is exactly 4.54609 L. Everything else is a fraction or multiple of those.
Worked example: a 5-gallon water jug
A water-cooler jug holds 5 US gallons. How many liters is that, and how heavy is it when full?
5 gal × 3.785411784 L/gal = 18.92705892 L
Water weighs about 1 kg per liter, so the water alone is about 18.93 kg, or 41.73 lb.
That matches the “about 42 pounds” warning printed on many jugs. An imperial 5-gallon container would hold 22.73 L instead.
Common volume conversions
| From | To | Multiply by |
|---|---|---|
| US gallons | liters | 3.785411784 (exact) |
| liters | US gallons | 0.2641721 |
| imperial gallons | liters | 4.54609 (exact) |
| imperial gallons | US gallons | 1.2009499 |
| cubic feet | US gallons | 7.4805195 |
| cubic feet | liters | 28.316846592 (exact) |
| cubic meters | US gallons | 264.17205 |
| US cups | milliliters | 236.5882365 (exact) |
| US fluid ounces | milliliters | 29.5735295625 (exact) |
| oil barrels | US gallons | 42 (exact) |
US, imperial and metric measures
US liquid measure
The US system builds up from the fluid ounce: 8 fl oz make a cup, 2 cups a pint, 2 pints a quart and 4 quarts a gallon. A US pint therefore holds 16 fl oz.
Imperial measure
British units use the same names with different sizes. The imperial fluid ounce (28.41 mL) is slightly smaller than the US one, but an imperial pint holds 20 of them, so a British pint (568.26 mL) is about 20% larger than an American pint (473.18 mL). The same 20% gap carries through quarts and gallons.
US dry measure
Grain, fruit and other dry goods were historically sold by a separate dry gallon of 268.8025 cubic inches. A bushel is 8 dry gallons, or 35.24 L, and a peck is a quarter of a bushel. Dry pints and quarts are about 16% larger than their liquid namesakes, so check which one a recipe or contract means.
Metric and cubic units
One milliliter equals one cubic centimeter (the “cc” on medical syringes), and 1,000 liters fill a cubic meter. For excavation and concrete, US contractors use cubic yards: 27 cubic feet, or about 0.7646 m³.
Where these units show up
Fuel and beverages are sold in liters or US gallons; water utilities often bill in hundreds of cubic feet (CCF, about 748 gallons); irrigation and reservoirs are measured in acre-feet (325,851 gallons, enough to cover an acre one foot deep); firewood is sold by the cord, a stack 4 × 4 × 8 ft holding 128 ft³. For kitchen amounts and ingredient weights, the cooking converter is a better fit, and the tank volume calculator works out how much a container holds from its dimensions.
Frequently asked questions
How many liters are in a gallon?
A US gallon is exactly 3.785411784 liters. An imperial (UK) gallon is larger, exactly 4.54609 liters. One liter is about 0.264 US gallons.
Is a liter bigger than a quart?
Slightly. One liter is about 1.057 US liquid quarts, and a US quart is 0.946 liters. An imperial quart, at 1.137 liters, is larger than both.
How many gallons are in a cubic foot?
About 7.48 US gallons. A US gallon is defined as exactly 231 cubic inches, and a cubic foot holds 1,728 cubic inches, so 1,728 ÷ 231 = 7.4805.
Why is an imperial gallon bigger than a US gallon?
They descend from different English gallons. The US kept the old wine gallon of 231 cubic inches, while Britain adopted a new gallon in 1824 defined by the volume of 10 pounds of water. Today the imperial gallon is fixed at exactly 4.54609 liters.