Fuel Cost Calculator
Calculate trip fuel cost, monthly and annual fuel spend. Compare two cars' efficiency. Supports mpg, L/100km, miles and kilometres.
How to use
UK vs US MPG
UK MPG and US MPG look like the same unit but aren't — the UK gallon is 4.546 litres, the US gallon is 3.785 litres (20% smaller). A car rated 50 mpg UK = about 41.6 mpg US. The L/100km figure is unambiguous and works the same worldwide.
Typical UK fuel prices (2026)
Petrol (unleaded): approximately 135-145p/litre. Diesel: approximately 140-150p/litre. These vary significantly by location (motorway services vs supermarket forecourts typically differ by 10-15p/litre) and by crude oil price. Use the AA fuel price tracker for current regional averages.
Frequently asked questions
Is the Fuel Calculator free to use?
Yes, the Fuel Calculator is completely free. There is no sign-up, no account required, and no limit on how often you can use it.
Is data from the Fuel Calculator saved between visits?
Some features use your browser's local storage to save data between visits on the same device. This data is not sent to any server and stays only on your device.
What devices does the Fuel Calculator work on?
The Fuel Calculator works on any device with a modern web browser — desktop, laptop, tablet, or phone. It is mobile-friendly and works offline once the page has loaded.