Convert any volume between ten units: millilitres, litres, cubic metres, US gallons, UK (imperial) gallons, US cups, US pints, US fluid ounces, UK fluid ounces, and metric teaspoons. Both sides are editable; swap flips the direction; five quick-pick buttons handle the most common pairs.
US vs UK: the gallon split
The single biggest landmine in volume conversion is the US / UK gallon distinction. They’re not equal:
- US (liquid) gallon: 3.785411784 L exactly (defined as 231 cubic inches)
- UK (imperial) gallon: 4.54609 L exactly (redefined 1985)
The UK gallon is about 20% larger. Every downstream imperial unit — pints, fluid ounces — is proportionally different too. Because silently merging them would corrupt recipe and fuel-economy values, the tool keeps them distinct. Pick the one that matches your source.
Example: recipe conversion
A US recipe calls for “1 cup of milk”. That’s 1 × 236.59 ≈ 237 mL. A UK recipe calling for “1 cup” probably means the UK imperial cup (284 mL), though less common — most UK recipes today use grams and mL directly.
US recipe: 1 cup, 2 tbsp butter, 1 tsp salt. Converting for a metric kitchen:
- 1 cup ≈ 237 mL
- 2 tbsp ≈ 30 mL
- 1 tsp = 5 mL
Example: fuel economy
30 US mpg → L/100km: 1 US gal / 30 mi × 1.609 km/mi = 0.0536 gal/km = 0.203 L/km = 20.3 L/100km. Wait, that’s too high — let me recompute: 1 gal = 3.785 L, 30 mi = 48.28 km, so 3.785 / 48.28 = 0.0784 L/km = 7.84 L/100km. OK. For 30 UK mpg: 4.546 L / 48.28 km × 100 = 9.42 L/100km. A UK 30 mpg uses more fuel per km than a US 30 mpg, because a UK gallon holds more fuel.
Example: bulk liquid
A 1 cubic metre IBC tank holds 1000 L ≈ 264.2 US gal ≈ 220 UK gal. A full 55-gallon US oil drum is 208 L. A 5-gallon US jug is 18.9 L.
What this tool does not do
It doesn’t handle dry measures. “1 cup of flour” is mass, not volume, and the density varies. For baking by weight (more accurate than by cup), use the weight converter.
It doesn’t support non-customary cups. Only the US customary cup (236.59 mL) is included. Metric (250 mL), US legal (240 mL), and UK imperial (284 mL) cups aren’t in the table.
It doesn’t include US dry gallons or US dry pints. Those exist for historical reasons but are almost never used in practice.
It doesn’t convert to bottle/can/serving sizes. “How many 355-mL soda cans fit in a US gallon?” is arithmetic beyond the converter’s scope. For area × depth calculations, combine the area converter with a depth figure.
It doesn’t support natural-language parsing. Enter a single numeric value — “1.5” not “one and a half”.