Volume Converter
Convert liquid and container volumes, with US and imperial (UK) gallons and fluid ounces kept clearly separate.
Result
Enter a value to convert.
How to use this calculator
- Enter a value and choose the from and to units.
- Check whether your recipe or fuel figure uses US or imperial (UK) units — they differ by about 20%.
- All units are listed below the result.
Formula
Every unit is converted through liters using exact definitions:
- 1 US gallon = 3.785411784 L
- 1 imperial gallon = 4.54609 L
- 1 US fluid ounce = 1/128 US gallon ≈ 29.5735 mL
- 1 imperial fluid ounce = 1/160 imperial gallon ≈ 28.4131 mL
- 1 US cup = 8 US fl oz ≈ 236.588 mL; 1 metric cup = 250 mL
- 1 m³ = 1,000 L
Worked example
5 gallons in liters
5 US gallons = 5 × 3.785411784 = 18.92705892 L.
5 imperial gallons = 5 × 4.54609 = 22.73045 L.
2 liters in US cups
2 ÷ 0.2365882365 = 8.453505675 US cups.
Assumptions and limitations
- “Cup” varies by country. The US customary cup (236.6 mL) and metric cup (250 mL) are both offered; the US “legal” cup used on nutrition labels (240 mL) is not.
- Dry volume measures such as US dry gallons and bushels are not included.
Frequently asked questions
Why is a UK gallon bigger than a US gallon?
They have different historical definitions. The imperial gallon is 4.54609 L and the US gallon is 3.785411784 L, so a UK gallon is about 20% larger.
How many milliliters are in a cup?
A US customary cup is about 236.6 mL and a metric cup (used in Australia, Canada and elsewhere) is 250 mL.