The Key Difference
There are two different gallons in common use and they are not interchangeable:
- US gallon: 3.78541 litres
- UK (Imperial) gallon: 4.54609 litres
The UK gallon is about 20% larger than the US gallon. This difference matters most for fuel economy comparisons, shipping and container volumes, cooking recipes from different countries, and purchasing liquids like paint, water containers, or fuel cans.
Conversion Formulas
| Conversion | Formula |
|---|---|
| Litres → US Gallons | ÷ 3.78541 |
| US Gallons → Litres | × 3.78541 |
| Litres → UK Gallons | ÷ 4.54609 |
| UK Gallons → Litres | × 4.54609 |
| US Gallons → UK Gallons | × 0.83267 |
| UK Gallons → US Gallons | × 1.20095 |
Quick Reference Table
| Litres | US Gallons | UK Gallons | Common Context |
|---|---|---|---|
| 1 L | 0.264 gal | 0.220 gal | Water bottle (large) |
| 2 L | 0.528 gal | 0.440 gal | Soda bottle |
| 3.785 L | 1.0 gal (US) | 0.833 gal | US gallon reference |
| 4.546 L | 1.201 gal | 1.0 gal (UK) | UK gallon reference |
| 10 L | 2.642 gal | 2.200 gal | Fuel can |
| 20 L | 5.283 gal | 4.399 gal | Large fuel can |
| 40 L | 10.57 gal | 8.799 gal | Small car fuel tank |
| 60 L | 15.85 gal | 13.20 gal | Average car fuel tank |
| 75 L | 19.81 gal | 16.49 gal | Large car / SUV tank |
| 100 L | 26.42 gal | 21.99 gal | Large container |
Why Fuel Economy Gets Confusing
The US measures fuel economy in miles per gallon (US), the UK measures in miles per gallon (Imperial), and most of Europe uses litres per 100 km. A car that gets 30 mpg in the US actually gets about 36 mpg by UK measurement and uses 7.84 L/100km — three completely different numbers for the same efficiency. Always check which gallon is being used before comparing fuel economy figures.
The volume converter below handles US gallons, UK gallons, litres, millilitres, fluid ounces, pints, quarts, and more — with the correct distinction between US and Imperial units.