Convert volume between litres, millilitres, cubic metres, cubic feet, US and Imperial gallons, quarts, pints and fluid ounces.
What Is a Volume Converter?
A volume converter translates capacity between metric and imperial units: 1 US gallon = 3.7854 litres, while 1 Imperial gallon = 4.5461 litres — the two gallons differ by 20%, the classic transatlantic fuel-economy confusion. The litre is defined from the cubic decimetre (1 L = 1,000 cm³), and the US gallon from the old English wine gallon (231 cubic inches). Recipes, fuel, tanks and aquariums all need these conversions.
How to Use the Volume Converter
- Enter the value.
- Pick the “from” unit — note US vs Imperial gallon.
- Pick the “to” unit.
- Click “Convert Volume”.
Volume Converter Formula
Convert to litres first (value × from-factor), then divide by the to-factor. All factors are exact definitions.
Worked Example
1 US gallon → litres: 1 × 3.785411784 = 3.7854 L. And 1 cubic foot → litres: 28.3168 L.
How It Works, In Plain Words
Rather than holding a separate conversion for every pair of units, the tool routes everything through one bridge unit: the litre. Each unit carries a factor that says how many litres it is worth — a US gallon carries 3.785411784, an Imperial gallon 4.54609, a cubic foot 28.316846592, and a millilitre just 0.001. Your value is multiplied by its own unit’s factor to become litres, then divided by the target unit’s factor to become the answer. In the worked example, 1 US gallon becomes 1 × 3.785411784 = 3.785411784 litres, and because the target is litres (factor 1), the division changes nothing and the display rounds it to 3.7854. The two-step route is why ten units can convert between each other in any direction without a hundred separate tables: pick any from-unit and any to-unit, and the same multiply-then-divide does the job. The factors are exact definitions, not measurements, so nothing is lost along the way — the only rounding happens at the end, when the result is shown to four decimal places.
Real-World Uses
Aquariums and water tanks are the first everyday case: tanks are often sized in cubic feet or gallons while treatments, pumps and water changes are measured in litres, and the page’s second example — 1 cubic foot = 28.3168 litres — is exactly the bridge you need. Fuel is the second: a car, a manual or a fuel-economy figure quoted in gallons only makes sense once you know which gallon it means and what it is in litres, which is why the fuel FAQ below tells you to check whether your country’s gallon is US or Imperial before multiplying. The third case is the kitchen, where recipes swap between quarts, pints, fluid ounces and millilitres; converting the liquid ingredients with one tool, in one pass, beats guessing at the side of a measuring jug — and because the tool works in both directions, a metric recipe can just as easily be turned back into the units your jug shows.
Benefits of Using the Volume Converter
- Ten units including both gallons — the confusion pair
- Exact defined factors
- Both directions in one tool
- Recipe, fuel, tank and aquarium friendly
Features of Our Tool
- Instant results in your browser
- No sign-up, no download, 100% free
- Works on mobile, tablet and desktop
- Clear step-by-step explanation below the tool
- Private — your entries never leave your device
Common Mistakes to Avoid
- Using the US gallon factor for an Imperial gallon — 20% off
- Mixing fluid ounces (volume) with ounces (weight) — different units entirely
- Forgetting the litre is 1,000 cm³ when converting from cubic measurements
More Common Mistakes to Avoid
The gallon mix-up tops the list: the Imperial gallon is about 20% larger than the US gallon, so converting with the wrong one quietly corrupts everything downstream — fuel figures, tank sizes, recipe scaling. Always settle which gallon a figure uses before you convert it. Next, keep fluid ounces and ounces apart: one measures volume, the other weight, and the tool’s fluid ounce is a volume unit only. With cubic units, remember the litre is 1,000 cm³, so a cubic metre is a large amount — the tool’s factor for it is 1,000 litres — not a small one; people who expect a modest number often re-enter the value in the wrong unit and compound the error. Finally, do not round halfway through a chain of conversions: convert once, with the exact factors, and let the tool round the final display.
Frequently Asked Questions
How many litres in a US gallon?
3.7854 litres.
What is the difference between US and Imperial gallons?
The Imperial gallon is 4.5461 L, about 20% larger than the US gallon’s 3.7854 L.
How many litres in a cubic foot?
28.3168 litres.
How many millilitres in a litre?
1,000 mL.
How do I convert gallons to litres for fuel?
Multiply US gallons by 3.7854 (check whether your country’s gallon is US or Imperial first).
How many litres are in a cubic metre?
1,000 litres. The tool’s factor for a cubic metre is 1,000, which follows from the litre’s definition — 1 L = 1,000 cm³, and a cubic metre holds a million cubic centimetres.
Why do US and Imperial gallons give different answers?
Because they are different sizes by definition: the US gallon is 3.7854 litres, from the old English wine gallon of 231 cubic inches, while the Imperial gallon is 4.5461 litres — about 20% larger. Pick the one your country, car or container actually uses.