Volume Converter
Volume conversions are everywhere in the kitchen, the garage and the garden — recipes in cups, fuel in gallons or litres, milk in pints, paint in litres. The catch is that “gallon”, “pint” and “ounce” mean different amounts in the US and the UK, so it’s essential to know which system your number comes from. This converter uses US customary units (the system used in US recipes and fuel pumps) alongside metric, and shows the exact factor used.
How to use the volume converter
- Enter the volume.
- Select the unit you have and the one you want.
- Check whether your recipe or product label is US customary or UK (imperial) — this converter is US customary.
Formula
All volumes convert through the litre: result = value × (litres per “from” unit) ÷ (litres per “to” unit). US customary exact definitions: 1 US gallon = 3.785411784 L, 1 quart = ¼ gallon, 1 pint = ⅛ gallon, 1 cup = 1/16 gallon (236.588 mL) and 1 fluid ounce = 1/128 gallon (29.5735 mL).
Worked examples
Fuel in litres
A 5-gallon US fuel can holds 18.927 litres.
A recipe in millilitres
Two US cups of milk is 473.18 mL, or 16 fluid ounces.
Litres to US gallons
A 60-litre tank is 15.85 US gallons.
Common volume conversions
| Conversion | Result |
|---|---|
| 1 gal | 3.78541 L |
| 1 qt | 0.946353 L |
| 1 cup | 236.588 mL |
| 1 floz | 29.5735 mL |
| 1 L | 33.814 floz |
| 1 gal | 16 cup |
US vs imperial
US customary and UK imperial volume units share names but not sizes: the imperial gallon (4.546 L) is about 20% larger than the US gallon (3.785 L), and an imperial pint (568 mL) is larger than a US pint (473 mL). This converter is US customary; for UK recipes with imperial measures, check which system the source uses before converting. See also the unit converter hub.
Practice problems
Try these yourself first, then check your answer. The answers come from the calculator above.
- A recipe needs 3 cups of milk. How many millilitres?
Show answer
3 cup in mL: 709.7647095
- A 14-gallon fuel tank holds how many litres?
Show answer
14 gal in L: 52.99576498
Common mistakes to avoid
- Using a US recipe with UK imperial cups or pints. A UK imperial pint is 568 mL, a US pint is 473 mL — about 20% different.
- Confusing fluid ounces (volume) with ounces (weight). A cup of flour does not weigh 8 oz.
- Forgetting that 1 litre is 1,000 mL and 1 m³ is 1,000 litres.
Frequently asked questions
How many litres are in a US gallon?
3.785411784 litres, exactly.
How many cups are in a gallon?
A US gallon holds 16 US cups (4 quarts × 2 pints × 2 cups).
Is a UK gallon the same as a US gallon?
No. A UK imperial gallon is 4.54609 litres, about 20% larger than a US gallon.
How many millilitres are in a cup?
A US customary cup is 236.588 mL. Many recipes round it to 240 mL (the “metric cup”).
How do I convert litres to gallons?
Divide the litres by 3.785411784. For 20 L: 20 ÷ 3.7854 = 5.28 US gallons.
Sources and further reading
Reviewed September 26, 2026 by the SolveCalcPro editorial team. Found a mistake? Tell us; see our editorial policy.