Gallon to Litre Converter
Convert between UK imperial gallons and litres instantly. Whether you’re working out fuel efficiency, following a recipe, or comparing measurements, this converter handles both imperial and US gallons with precision.
Quick Conversions
Gallon to Litre Conversion Table
Here are the most common gallon to litre conversions for UK imperial gallons. These values are particularly handy when you’re dealing with fuel consumption figures or larger liquid volumes.
| UK Gallons | Litres | US Gallons |
|---|---|---|
| 1 | 4.546 | 1.201 |
| 2 | 9.092 | 2.402 |
| 3 | 13.638 | 3.603 |
| 4 | 18.184 | 4.804 |
| 5 | 22.730 | 6.005 |
| 10 | 45.461 | 12.010 |
| 15 | 68.191 | 18.014 |
| 20 | 90.922 | 24.019 |
| 25 | 113.652 | 30.024 |
| 30 | 136.383 | 36.029 |
| 40 | 181.844 | 48.038 |
| 50 | 227.305 | 60.048 |
| 75 | 340.957 | 90.071 |
| 100 | 454.609 | 120.095 |
Conversion Formula
The maths behind converting gallons to litres is straightforward. You multiply the number of gallons by the conversion factor specific to the type of gallon you’re working with.
UK Imperial Gallon to Litre
Litres = Gallons × 4.54609
Example: 5 imperial gallons = 5 × 4.54609 = 22.73 litres
US Gallon to Litre
Litres = Gallons × 3.78541
Example: 5 US gallons = 5 × 3.78541 = 18.93 litres
Litre to UK Imperial Gallon
Gallons = Litres ÷ 4.54609
Example: 20 litres = 20 ÷ 4.54609 = 4.40 imperial gallons
Imperial vs US Gallon
There’s a significant difference between UK imperial gallons and US gallons. The imperial gallon is roughly 20% larger, which matters when you’re comparing fuel economy figures or following American recipes.
UK Imperial Gallon
Used in the UK for MPG figures and traditionally for petrol sales. Still appears on fuel efficiency labels for British vehicles.
US Gallon
Standard in the United States. About 20% smaller than the imperial gallon, affecting direct comparisons.
UK Gallon
US Gallon
Where Gallons Matter in Britain
Whilst petrol stations across the UK switched to selling fuel by the litre decades ago, the gallon hasn’t disappeared entirely. Miles per gallon (MPG) remains the standard way to discuss fuel economy. Car manufacturers still list MPG figures alongside litres per 100 kilometres.
You’ll also encounter gallons in older British recipes, particularly when dealing with large batch cooking or brewing. Many traditional measurements haven’t been fully metricated, especially in home brewing circles where imperial gallons persist.
Another place gallons pop up is in comparing vehicles with American specs. A car achieving 30 MPG in the US actually gets about 36 MPG in UK terms because of the gallon size difference. This catches out many people comparing vehicles across the Atlantic.
Everyday Conversions
Fuel Tank
A typical family car’s 50-litre tank equals about 11 imperial gallons. That’s roughly 13.2 US gallons.
Large Recipe
A gallon of stock for batch cooking converts to 4.5 litres. Perfect for scaling recipes from imperial to metric.
Home Brewing
A 5-gallon brewing batch equals 22.7 litres. Many home brewing kits still reference imperial gallons.
Water Usage
Average UK household uses about 330 litres daily, equivalent to roughly 72.6 imperial gallons per day.
Volume Unit Conversions
Beyond gallons and litres, here are other volume conversions you might find handy. These cover the common liquid measurements used in the UK and internationally.
| From | To | Multiply By |
|---|---|---|
| UK Gallons | Litres | 4.54609 |
| US Gallons | Litres | 3.78541 |
| UK Pints | Litres | 0.568261 |
| US Pints | Litres | 0.473176 |
| Litres | Millilitres | 1,000 |
| Litres | Fluid Ounces (UK) | 35.1951 |
| Litres | Fluid Ounces (US) | 33.814 |
| Cubic Metres | Litres | 1,000 |
FAQs
How many litres are in a UK gallon?
One UK imperial gallon equals exactly 4.54609 litres. This is the gallon used for MPG figures in Britain and historically for petrol sales before metrication.
Is a UK gallon the same as a US gallon?
No. A UK imperial gallon contains 4.546 litres, whilst a US gallon holds only 3.785 litres. The imperial gallon is approximately 20% larger, which significantly affects fuel economy comparisons between British and American vehicles.
Why does the UK still use MPG if petrol is sold in litres?
It’s a holdover from when petrol was sold by the gallon. The switch to litres at the pump happened in the 1990s, but MPG stuck around because drivers were familiar with it. Most car displays now show both MPG and litres per 100 kilometres.
How do I convert 10 gallons to litres?
For UK imperial gallons: 10 × 4.54609 = 45.46 litres. For US gallons: 10 × 3.78541 = 37.85 litres. Always check which gallon type you’re converting from.
What’s 20 litres in gallons?
Twenty litres equals 4.40 UK imperial gallons or 5.28 US gallons. To convert litres to imperial gallons, divide by 4.54609. For US gallons, divide by 3.78541.
Which gallon should I use for UK recipes?
British recipes traditionally use imperial gallons. If you’re following an old cookbook or a brewing recipe, assume imperial unless stated otherwise. Modern recipes usually specify litres directly.
How many litres in a half gallon?
Half a UK imperial gallon equals 2.273 litres. Half a US gallon equals 1.893 litres. This size is common in older milk containers and some brewing applications.
Can I use this converter for fuel efficiency comparisons?
Yes, but remember that MPG figures from the US and UK aren’t directly comparable even after conversion. UK MPG uses imperial gallons and miles, whilst US MPG uses US gallons and miles. A car rated at 30 US MPG equals roughly 36 UK MPG.