Volume & Liquid Capacity Converter
Convert a volume or liquid capacity between twenty units, spanning metric litres, US customary measures and imperial measures. The important catch is that US and imperial units of the same name are not the same size — a US gallon is about 3.785 litres while an imperial gallon is about 4.546 litres, and US and imperial pints, fluid ounces and cups differ too. This converter keeps them clearly separate so a recipe or fuel figure never gets silently mixed up between the two systems.
How to use this tool
- Type the volume you want to convert into the Value field.
- Pick the unit your number is currently in — watch whether it is US or imperial.
- Pick the unit you want the answer in from the To menu.
- Read the result as you type — there is no button to press.
- Switch on “Show every equivalent unit” to compare US, imperial and metric measures side by side.
The formula
Volume uses the litre as its base unit. Volume is length cubed, so the cubic ratios grow quickly: a cubic metre holds a thousand litres.
litres = value × L_per_unit
result = litres ÷ L_per_target- L_per_unit
- Litres in one unit of the input
- US gallon
- Exactly 231 cubic inches, or 3.785411784 L
- Imperial gallon
- Exactly 4.54609 L — about 20% larger
US and imperial units share names but not sizes. A US pint is 473 mL while an imperial pint is 568 mL, so recipes and fuel figures do not transfer between the two systems without converting.
Worked examples
Litres to US gallons for fuel
- Given
- 1 litre
- Result
- 0.264172 US gallons
1 L ÷ 3.785411784 L per US gallon = 0.2642 gal. A US gallon is defined as exactly 231 cubic inches.
US vs imperial gallon
- Given
- 1 imperial gallon
- Result
- 1.200950 US gallons
An imperial gallon (4.54609 L) is about 20% larger than a US gallon (3.785 L), so it is 1.201 US gallons — a common source of confusion.
Cups to millilitres for cooking
- Given
- 1 US cup
- Result
- 236.588237 millilitres
A US cup is 236.59 mL, whereas a metric cup is exactly 250 mL — another reason to check which system a recipe uses.
Frequently asked questions
They were standardised separately. The US gallon is defined as 231 cubic inches (about 3.785 litres), based on an old English wine gallon, while the imperial gallon (about 4.546 litres) was defined later in Britain as the volume of ten pounds of water. The imperial gallon is roughly 20% larger, so US and imperial figures must never be mixed.
No. A US pint is about 473 mL and an imperial pint is about 568 mL — the imperial pint is around 20% larger, the same ratio as the gallons. This is why a UK pint of beer is noticeably more than a US pint. This converter lists them separately.
A US cup is 236.588 mL, while a metric cup (used in Australia, New Zealand and much of Europe) is exactly 250 mL. The difference is small but matters in baking, so check which your recipe assumes. Both are included here.
It depends on the system: a US teaspoon is about 4.929 mL, a metric teaspoon is exactly 5 mL, and an imperial teaspoon is about 5.919 mL. For most cooking the differences are minor, but the converter keeps them distinct for precision.
Yes, they derive from exact definitions — the US gallon as 231 cubic inches, the litre as a cubic decimetre, and so on. Only the final displayed value is rounded. Because so many same-named units differ between systems, the labels always state US, imperial or metric.
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