Fuel cost calculator
Work out what a journey costs in fuel, and what each passenger owes.
- Runs in your browser — nothing you enter is uploaded
- No sign-up, no quotas, free to use as often as you like
How it works
Working out what a drive actually costs matters for splitting it with passengers, claiming it back, or deciding whether to drive at all. The arithmetic is easy and the units are the part that catches people out.
Both measurement systems
Metric uses litres per 100 kilometres, where a lower number is better. Imperial uses miles per gallon, where a higher number is better — the two run in opposite directions, which is a reliable source of confusion. Pick the one your car's display uses.
US and UK gallons differ
A US gallon is about 3.79 litres and a UK gallon about 4.55, so a figure quoted in UK mpg looks about 20% better than the same car quoted in US mpg. This calculator uses US gallons for the imperial option, which is what mpg means in North America.
Real consumption is worse than the official figure
Manufacturer figures are measured under test conditions. Real driving — cold starts, hills, traffic, a loaded car, air conditioning, motorway speeds — typically uses 10 to 25% more. Using your own observed figure gives a much better answer than the brochure number.
Fuel is not the whole cost
Tyres, servicing, depreciation and wear are real costs per mile that this does not include. For reimbursement, official mileage rates exist precisely because they cover all of that, and they are considerably higher than fuel alone.
Fuel cost calculator — questions
Which is better, a low or high consumption figure?
Low is better for litres per 100 km; high is better for miles per gallon. They run in opposite directions.
Does it use US or UK gallons?
US gallons, which is what mpg means in North America. A UK gallon is about 20% larger.
Why is my real cost higher?
Official consumption figures come from test conditions. Real driving typically uses 10 to 25% more, and fuel is not the only cost per mile.