To convert liters to US gallons, divide by 3.78541, so 1 liter is 0.2642 US gallons. For UK (imperial) gallons, divide by 4.54609 instead. The two gallons differ by about 20%, which is the single biggest source of volume conversion errors. Our free volume converter handles both gallons plus liters, milliliters, cubic meters, cups, fluid ounces, tablespoons and teaspoons.
Volume conversion turns up in fuel tanks, recipes, aquariums, garden projects and drink bottles. Metric volume is simple because everything scales by 1,000. US and imperial units take more care, because the same name can mean two different sizes.
Metric volume units
- 1 liter (L) = 1,000 milliliters (mL)
- 1 milliliter = 1 cubic centimeter (cm³, often written cc)
- 1 liter = 1,000 cm³, the volume of a cube 10 cm on each side
- 1 cubic meter (m³) = 1,000 liters
A liter of water has a mass of about 1 kilogram, which is why metric recipes and lab work move easily between volume and weight for water. For other liquids and dry ingredients the weight depends on density.
US and imperial volume units
US customary units follow a chain: 1 gallon = 4 quarts = 8 pints = 16 cups = 128 fluid ounces. In the kitchen, 1 cup = 8 fl oz = 16 tablespoons, and 1 tablespoon = 3 teaspoons.
The UK imperial system uses the same names for larger sizes:
| Unit | US customary | UK imperial |
|---|---|---|
| Gallon | 3.785 L | 4.546 L |
| Quart | 946.35 mL | 1,136.52 mL |
| Pint | 473.18 mL | 568.26 mL |
| Fluid ounce | 29.57 mL | 28.41 mL |
| Cup | 236.59 mL | Not standard; many recipes outside the US use a 250 mL metric cup |
Note the odd one out: the imperial pint and gallon are bigger than the US versions, but the imperial fluid ounce is slightly smaller. An imperial pint holds 20 imperial fluid ounces, while a US pint holds 16 US fluid ounces.
The volume conversion formula
result = value × (liters per "from" unit) ÷ (liters per "to" unit)
L → US gal: US gal = L ÷ 3.78541
L → UK gal: UK gal = L ÷ 4.54609
US cups → mL: mL = cups × 236.588
US gal → L: L = US gal × 3.78541Worked examples
Liters to gallons for a fuel tank
A 50-liter fuel tank holds 50 ÷ 3.78541 = 13.21 US gallons, or 50 ÷ 4.54609 = 11.00 UK gallons. Same tank, two answers, so always check which gallon a figure uses.
Cups and spoons to milliliters
A recipe calls for 1.5 US cups of stock: 1.5 × 236.588 = 354.88 mL. Three tablespoons of oil is 3 × 14.7868 = 44.36 mL. When a recipe gives dry ingredients in cups, you need a weight conversion instead; the cooking converter uses ingredient density for that, and our guide to precision cooking conversions explains why. To make a recipe bigger or smaller, the recipe scaler adjusts every quantity at once.
Tank or container volume from its dimensions
An aquarium measures 120 cm × 50 cm × 50 cm.
- Multiply the sides: 120 × 50 × 50 = 300,000 cm³.
- Since 1,000 cm³ is 1 liter, that is 300 liters.
- Convert: 300 ÷ 3.78541 = 79.25 US gallons.
Measured in inches, a 48 × 20 × 20 in tank holds 19,200 cubic inches. A US gallon is exactly 231 cubic inches, so that is 19,200 ÷ 231 = 83.12 US gallons. For garden beds and slabs, find the floor area first with the area converter, then multiply by the depth; our area conversion guide shows how.
How to use the Volume Converter
- Open the Volume Converter. It starts at 1 liter to US gallons, which shows 0.2642.
- Enter your amount in the Value field. Decimals work; negative values are rejected.
- Choose the starting unit in the From list: liters, milliliters, cubic meters, cubic centimeters, gallons (US), gallons (UK), quarts, pints, cups, fluid ounces, tablespoons or teaspoons.
- Choose the target unit in the To list.
- Read the Result, rounded to four decimal places. It updates as you type.
- Use the swap button to reverse the conversion.
In this converter, quarts, pints, cups, fluid ounces, tablespoons and teaspoons are US customary sizes. Only the gallon comes in both US and UK versions. To convert a UK pint, divide by 8 and enter the result as gallons (UK): 2 UK pints is 0.25 UK gallons, which converts to 1.1365 liters. The tool has no cubic inch or cubic foot option, so use 231 cubic inches per US gallon, or 28.3168 liters per cubic foot.
Common volume conversion mistakes
- Mixing US and UK gallons. A UK gallon is about 1.2 US gallons. Fuel economy, tank sizes and paint coverage figures change by 20% depending on which one is meant.
- Assuming every cup is the same. A US customary cup is 236.6 mL, a metric cup is 250 mL, and US nutrition labels round a cup to 240 mL. Tablespoons vary too: an Australian tablespoon is 20 mL, against about 14.8 mL in the US.
- Treating fluid ounces as weight ounces. A fluid ounce measures volume. A fluid ounce of water weighs about one ounce, but a fluid ounce of honey weighs much more.
- Getting cubic units wrong by a factor of 10. One cubic meter is 1,000 liters, not 100, and one cubic centimeter is exactly one milliliter.
Daily water targets are quoted in liters in some places and in cups or fluid ounces in others. The water intake calculator gives an estimate in liters, cups and bottles, and this converter translates it to whatever unit you prefer. Our guide to staying hydrated covers what affects the target. It is a general estimate, not medical advice.
Frequently asked questions
How many liters are in a gallon?
A US gallon is 3.785 liters and a UK (imperial) gallon is 4.546 liters. One liter is 0.2642 US gallons or 0.22 UK gallons.
How many cups are in a liter?
One liter is about 4.23 US customary cups. Using 250 mL metric cups, it is exactly 4 cups.
How many milliliters are in a cup?
A US customary cup is 236.588 mL. A metric cup is 250 mL, and US nutrition labels use 240 mL.
How many fluid ounces are in a liter?
One liter is 33.81 US fluid ounces or 35.20 imperial fluid ounces.
Is a milliliter the same as a cc?
Yes. One milliliter is exactly one cubic centimeter (cc or cm³), so the two can be used interchangeably.
How many teaspoons are in a tablespoon?
There are 3 teaspoons in a US tablespoon. A US tablespoon is about 14.8 mL and a teaspoon about 4.9 mL.