Volume Converter

Easily convert between volume units like liters, cubic meters, gallons. A useful tool for liquid measurements, tank volumes, and other volume calculations.

From Unit

To Unit

How to Use Volume Converter?

1. Enter the volume value you want to convert
2. Select the source unit (e.g. liters)
3. Select the target unit (e.g. gallons)
4. Click the "Convert" button

Tips:
- Use dot (.) for decimal numbers
- Negative values are not allowed
- Results are shown up to 4 decimal places for precision
- All common volume units are supported

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Volume conversion, and the gallon that is not a gallon

Volume has the most dangerous ambiguity in measurement: the US and imperial gallons differ by 20%, and their pints, quarts, and fluid ounces differ too - in inconsistent directions. Recipes and fuel figures crossing the Atlantic are wrong far more often than people realise.

Formula

target = source x (source factor to litres / target factor to litres)

One litre is exactly one cubic decimetre, and one cubic metre is exactly 1,000 litres. These relationships are definitional.

US and imperial units are not the same

The imperial gallon was defined in 1824 as the volume of ten pounds of water. The US gallon derives from the older English wine gallon of 231 cubic inches. They were never reconciled.

US gallon: 3.78541 litres. Imperial gallon: 4.54609 litres. The imperial is 20.1% larger.
US pint: 473.176 ml. Imperial pint: 568.261 ml. The imperial is 20.1% larger.
US fluid ounce: 29.5735 ml. Imperial fluid ounce: 28.4131 ml. Here the US is 4.1% larger - the ratio reverses.
The reversal happens because a US gallon has 128 fluid ounces while an imperial gallon has 160. Assuming the pattern holds across all units is where recipes go wrong.

Cooking measures are worse than the gallon problem

A US cup is 236.6 ml, but the "metric cup" used in Australia, New Zealand, and much of Europe is 250 ml, and the Japanese cup is 200 ml. A recipe calling for two cups can vary by 100 ml depending on origin.

Tablespoons are equally inconsistent: 14.79 ml in the US, 15 ml metric, and 20 ml in Australia. A recipe with four Australian tablespoons of an ingredient uses 80 ml where a US cook would use 59 ml.

For baking, where ratios matter, weight is far more reliable than volume. A cup of flour ranges from about 120 g to 150 g depending on whether it was scooped or spooned, which is a 25% variation from measurement technique alone.

Fuel economy figures do not compare directly

Miles per gallon in the UK and the US use different gallons, so UK figures are inherently about 20% higher for identical consumption.

A car rated 40 mpg in the UK is 33.3 mpg in US terms, and both are 7.06 litres per 100 km. Only the metric figure allows direct comparison.

Note also that mpg and l/100km are reciprocals, so they are not linearly related. Improving from 20 to 25 mpg saves far more fuel over a fixed distance than improving from 40 to 45 mpg, despite both being a 5 mpg gain.

Worked example

A US recipe calls for 2 cups of stock, 1 pint of cream, and half a US gallon of water.

Stock: 2 x 236.6 = 473.2 ml. Cream: 473.2 ml. Water: 0.5 x 3,785.41 = 1,892.7 ml, so 1.89 litres.

Using imperial equivalents instead would give 1,136 ml of stock at 568 ml per cup - more than double - and 2.27 litres of water. The dish would be substantially over-diluted, which is exactly how cross-Atlantic recipe failures happen.

Volume units in litres

Unit	US	Imperial / metric
fluid ounce	0.0295735	0.0284131
cup	0.236588	0.250 (metric cup)
pint	0.473176	0.568261
quart	0.946353	1.136523
gallon	3.785412	4.546090
tablespoon	0.0147868	0.015 (metric)
cubic metre	1,000	1,000

The imperial fluid ounce is smaller than the US one, while every larger imperial unit is bigger. The pattern does not hold across the family.

Frequently Asked Questions

About 20.1%. An imperial gallon is 4.54609 litres against 3.78541 for the US gallon. This is why UK and US fuel economy figures cannot be compared without conversion.

Because the two systems divide the gallon differently. A US gallon contains 128 fluid ounces while an imperial gallon contains 160, so the imperial ounce ends up smaller despite the larger gallon.

Yes, since 1964. Between 1901 and 1964 the litre was defined as the volume of one kilogram of water at maximum density, which made it about 28 parts per million larger. Precision measurements from that era need care.

Match the recipe origin: 236.6 ml for the US, 250 ml for Australia, New Zealand, and metric European recipes, and 200 ml for Japan. For baking, weighing ingredients avoids the problem entirely.

Divide 235.215 by US mpg, or 282.481 by imperial mpg. The relationship is reciprocal, not linear, which is why equal mpg gains produce unequal fuel savings.

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References

Last reviewed: 2026-08-07. This page is informational. For legal, medical, tax, or financial decisions, confirm the result with a qualified professional.