Quick answer: Volume measures three-dimensional space in cubic units. Common formulas: box length times width times height, cylinder pi r squared times height, sphere four-thirds pi r cubed. Key conversions: one liter is 1000 cubic centimeters, one US gallon is 3.78541 liters, and one US cup is 236.588 milliliters.
Last reviewed: September 2026
Key facts
- 1 US gallon = 3.78541 litres; 1 litre = 0.264172 US gallons.
- 1 US cup = 236.588 ml; 1 fluid ounce = 29.5735 ml.
- US and imperial gallons differ — an imperial gallon is 4.54609 L (20% larger).
- A metric cup is 250 ml, slightly bigger than the US cup.
Recipes, fuel economy, aquariums — volume units are a maze of gallons, cups and litres. This free volume converter switches between millilitres, litres, cubic metres, teaspoons, tablespoons, fluid ounces, cups, pints, quarts and gallons instantly.
Enter a value and pick your units. Watch the gallon: US and imperial gallons are different sizes, and the converter uses US gallons unless you choose otherwise.
How to use
- Enter a value.
- Pick the from and to units.
- Read the answer and the full table of equivalents below.
How volume conversion works
| Term | Meaning |
|---|---|
| from-unit in litres | Each unit’s exact definition in litres. |
| to-unit in litres | The target unit’s definition in litres. |
Volume is cubed length: 1 litre is exactly 1 cubic decimetre (1,000 cm³).
Worked examples
Fuel and drink
2 litres → US gallons: 2 ÷ 3.78541 = 0.528 gal.
1 US gallon → litres: 3.78541 L.
Cooking measures
500 ml → fl oz: 500 ÷ 29.5735 = 16.91 fl oz.
2 US cups → ml: 2 × 236.588 = 473.18 ml — just under half a litre.
Volume units in litres
| Unit | Equals (L) | Used for |
|---|---|---|
| Millilitre (ml) | 0.001 | Medicine, small recipes |
| Litre (L) | 1 | Drinks, fuel (metric) |
| Cubic metre (m³) | 1,000 | Pools, rooms, freight |
| Teaspoon (US tsp) | 0.00492892 | Cooking, medicine |
| Tablespoon (US tbsp) | 0.0147868 | Cooking (3 tsp) |
| Fluid ounce (fl oz) | 0.0295735 | US drinks, bottles |
| Cup (US) | 0.236588 | US recipes |
| Pint (US pt) | 0.473176 | Milk, beer (US) |
| Quart (US qt) | 0.946353 | Just under a litre |
| Gallon (US gal) | 3.78541 | US fuel, jugs |
Imperial (UK) versions are larger: 1 imperial gallon = 4.54609 L, 1 imperial pint = 568.261 ml.
Frequently asked questions
Litres to gallons — which gallon?
The converter uses US gallons (3.78541 L). Imperial gallons (4.54609 L) are 20% larger — check which your source means.
How many ml in a US cup?
236.588 ml. A metric cup is 250 ml, so the two differ by about 5% — enough to matter in baking.
How many litres in a cubic metre?
1,000. A cubic metre of water weighs exactly one metric tonne.
Why do US and UK pints differ?
The US kept the old 16-ounce pint while Britain redefined its pint as 20 ounces in 1824 — then the two systems drifted further apart.
What is a fluid ounce vs an ounce?
Fluid ounces measure volume (29.5735 ml); ounces measure weight (28.3495 g). For water they nearly match, but not for other liquids.
Sources
Key takeaways
- 1 US gal = 3.78541 L; 1 L = 0.264172 gal; 1 cup = 236.588 ml.
- US and imperial gallons/pints differ — confirm which one a recipe or spec means.
- 1 litre = 1 cubic decimetre = 1,000 cm³, exactly.
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