Volume Converter
Convert volume between metric and both US and UK measuring units - kept properly separate.
What this tool does
To convert volume, multiply by the exact factor between the two units - but check which country's units are meant first: a US gallon (3.785411784 litres) and a UK/imperial gallon (4.54609 litres) differ by about 20%, and the same gap applies to pints, quarts and fluid ounces. This tool lists US and UK units explicitly and separately, alongside millilitres, litres and cubic metres, so the conversion is never ambiguous about which system it used.
Converts volume between fourteen units - metric (millilitres, litres, cubic metres) plus US units (teaspoon, tablespoon, fluid ounce, cup, pint, quart, gallon) and UK/imperial units (fluid ounce, pint, quart, gallon) kept fully separate.
Shows the exact factor used, so it's clear which country's definition produced the result.
How to use it
- Enter the volume you want to convert.
- Pick the unit you're converting from - checking carefully whether it's a US or UK unit if it's a cup, pint, quart or gallon.
- Read the result, or press Swap units to reverse it.
Why use this converter
US and UK cups, pints and gallons are different sizes with the same names, and recipes, fuel and drinks labels do not always say which. Naming the exact unit prevents a 20% error on the quantity.
Why we built it
We built the volume converter to list US and UK units separately because a US and a UK gallon differ by about 20%. For recipes use the cups to ml converter and for fuel the litres to gallons converter.
Related tools worth a look: the Pool Volume Calculator.
Who this tool is for
- Cooks and bartenders
- Home brewers and gardeners
- Students and travellers
When to use it
- Following a recipe from the US or the UK.
- Comparing fuel, drink or cleaning-product sizes.
- Sizing tanks, containers and pools in litres or gallons.
- Converting laboratory or medical volumes.
US and UK volume units are not interchangeable
The single biggest source of wrong answers in volume conversion.
A US gallon is defined as exactly 231 cubic inches, which works out to 3.785411784 litres. A UK (imperial) gallon is defined differently - as the volume of 10 pounds of water - and comes to exactly 4.54609 litres, about 20% more. The same ratio carries through to pints, quarts and fluid ounces, since each is a fixed fraction of its own country's gallon. A recipe or a fuel-efficiency figure that doesn't say which gallon it means is genuinely ambiguous, and treating them as the same unit is the most common volume-conversion mistake.
This tool lists 'US gallon' and 'UK gallon' as distinct, clearly labelled units rather than a single generic 'gallon,' precisely so that choice is made deliberately rather than assumed.
Cooking measurements: cups, tablespoons, teaspoons
US cooking measurements (cup, tablespoon, teaspoon) are volume units, standardised in the US customary system: 1 US cup is 16 US tablespoons, and 1 US tablespoon is 3 US teaspoons. The UK doesn't use the cup as a standard cooking measure in the same way; UK recipes more often specify millilitres or imperial fluid ounces directly. If a recipe from a different country gives you cups and the result looks off, check first which cup-style measurement system it's using.
What you give it, and what you get back
| Item | Details |
|---|---|
| Value | A number in the "from" unit. |
| From and To | Metric units plus separate US and UK/imperial teaspoons, cups, pints, quarts and gallons. |
| Output | The converted volume and the factor used. |
Issues you may run into
| What you see | Why it happens | What to do |
|---|---|---|
| Result is about 20% different from a recipe | US and UK units differ. | Pick the US or UK version explicitly. |
| Need grams from cups | Volume to weight depends on the ingredient. | Use the mL to grams converter. |
| Pint looks wrong | A US pint is 16 fluid ounces; a UK pint is 20. | Check the country of your source. |
Assumptions and limitations
- Cooking-ingredient conversions between volume and weight (grams per cup, for instance) vary by ingredient density - for that, use the dedicated cooking measurement converter, not this volume-only tool.
- This lists US and UK/imperial units explicitly; if a source uses a plain 'gallon,' 'pint' or 'cup' without saying which, check the source's country before assuming.
- Very small or very large results are shown with practical rounding for readability; the internal calculation is exact.
Frequently asked questions
What is the difference between a US gallon and a UK gallon?
A US gallon is 3.785411784 litres; a UK (imperial) gallon is 4.54609 litres - about 20% more. They come from different historical definitions and are not interchangeable, so always check which one a source is using.
How many cups are in a litre?
About 4.2 US cups, since 1 US cup is exactly 0.2365882365 litres. The UK doesn't use a standard 'cup' measurement the same way, so if a recipe is in UK/imperial units, it will typically give millilitres or fluid ounces instead.
How many millilitres are in a tablespoon?
A US tablespoon is exactly 14.7867647813 millilitres (about 15 mL in everyday rounding). A UK tablespoon is conventionally treated as 15 mL as well in most recipes, though the two aren't defined identically.
Is a US pint the same as a UK pint?
No. A US pint is 473.176473 mL; a UK pint is 568.26125 mL - about 20% more, the same ratio as the gallon they're both derived from.
How many fluid ounces are in a cup?
8 US fluid ounces make 1 US cup, exactly. The UK's imperial fluid ounce is a different size again, so a UK-fluid-ounce measurement doesn't convert to US cups using the same 8-to-1 ratio.
Why does this converter list US and UK units separately instead of just 'gallon' or 'pint'?
Because they're genuinely different sizes - roughly 20% apart for gallons, pints and quarts - and merging them into one generic unit would silently produce a wrong answer for whichever country wasn't meant. Listing them separately makes the choice explicit.
Sources and accuracy
Exact internationally defined constants for US customary and UK imperial volume units, and the exact 231 cubic inch US gallon / 4.54609 L UK gallon definitions.
Figures last checked against the source on . Standards and rates can change — if you are relying on this for something that matters, confirm against the source above. Think a figure is wrong or out of date? Send a correction.