Liter to Gallon Converter — US, Imperial & Quick Formula

US Gallon vs Imperial Gallon vs Litre — Side-by-Side Comparison

The confusion between litres, US gallons and imperial gallons comes from the fact that the word gallon means two different volumes depending on which side of the Atlantic your grandparents were born on. The table below sets them down next to each other so you can see at a glance what you are dealing with when a supplier quotes a tank in "gallons" without specifying which one.

Why the UK Gallon is 4.5 Litres but the US Gallon is 3.8 Litres

The split between the US and imperial gallon is a story of wine, ale and an Act of Parliament. Medieval England used several gallons concurrently: the wine gallon of 231 cubic inches, the ale gallon of 282 cubic inches, and the corn gallon of 268.8 cubic inches. When the United States declared independence in 1776 it inherited the wine gallon, which had been the legal standard for imported goods since the 15th century. America codified it as 231 cubic inches in the Weights and Measures Act of 1792, and that number has not changed since.

Back in Britain, the Weights and Measures Act of 1824 discarded the old wine, ale and corn gallons and defined a single imperial gallon as "the space occupied by ten pounds weight of distilled water at 62 degrees Fahrenheit and 30 inches of mercury pressure" — which came out to exactly 277.42 cubic inches, or 4.54609 litres. This became the legal definition throughout the British Empire, and countries as far apart as Australia, India and Nigeria still use gallon numbers from this standard when quoting vintage equipment or discussing fuel economy in miles per gallon.

The practical consequence is that an imperial gallon is about 20% larger than a US gallon. A car that does 30 miles per US gallon is doing roughly 36 miles per imperial gallon — which is why old brochures from British car makers always quote higher mpg numbers than their American counterparts using the same engine.

Quick Reference Formula Cards

Memorising six decimal coefficients sounds like a chore, but you only need two of them in your head — the rest fall out by division. Copy these cards into your notes or hit print before you place that tank order across borders.

Litre-to-Gallon Conversion Table — 1 to 100 Litres

For batch planning — sizing a bank of water tanks, ordering jerrycans, or checking how many trip-serving bottles fit a drum — the full table below covers every whole litre from 1 through 100 with both US and imperial gallon equivalents rounded to four decimal places. Cubic metres are included so you can chain straight into the SI system for engineering calculations.

Common Real-World Sizes — Litres, US Gallons & Imperial Gallons

The confusion between litre and gallon almost always surfaces with a specific object — a fridge water tank, a caravan jerrycan, a barrel of oil. Below are the numbers you are most likely to see quoted, with both gallon versions side by side so you can spot a specification error at a glance.

Frequently Asked Questions