Gallons to Liters Converter

What this tool is used for

• Converting a US or UK fuel volume into metric for a specification.
• Reading an imperial tank capacity against a metric requirement.
• Converting a gallon-based recipe volume for metric equipment.
• Comparing imperial product sizes against metric ones.
• Converting a flow rate's volume component into metric units.

Frequently Asked Questions

Why does the quick reference stop at 55 gallons?

Because the 55-gallon drum is the standard industrial container in the US, at 208.2 L. Its metric counterpart is the 200-litre drum, which is about 52.8 US gallons — the two look interchangeable on a pallet and differ by roughly eight litres, which matters when costing a shipment.

Which gallon does a car's fuel economy use?

It depends on the country, and the difference is large enough to mislead. US mpg figures use the 3.785 L gallon and UK ones the 4.546 L imperial gallon, so the same car scores about 20% higher in the UK. Canada abandoned both and rates consumption in L/100 km.

Where does the imperial gallon's odd size come from?

From water. It was defined in 1824 as the volume of ten pounds of water at 62 °F, which produced 4.54609 L — a figure later fixed exactly rather than re-derived. The US gallon has a different origin entirely: the old English wine gallon of 231 cubic inches.

How exact are these factors?

Both are exact by definition, and the tool shows them rounded. A US gallon is exactly 3.785411784 L, because 231 cubic inches at 2.54 cm to the inch leaves no ambiguity; an imperial gallon is exactly 4.54609 L by statute. Nothing here is measured — it is all definitional.

Why show millilitres as well?

Because small volumes are where gallon arithmetic is least intuitive and most needed — a quarter gallon is 946.4 mL, close enough to a litre to be confused with one at a glance but 5% short. Recipes and lab work quote millilitres, so the second row saves a mental step.

Common errors and gotchas

• Not stating which gallon. US and imperial differ by about 20%, and both are simply called gallons.
• Using the liquid gallon for a dry measure, which is a different volume in US units.
• Rounding on a small volume where the absolute error matters.
• Converting a fuel-economy figure with only the volume factor, forgetting the distance unit.
• Assuming a labelled capacity is the exact volume rather than a nominal one.