Fuel Cost Calculator
Work out what a journey costs in fuel from the distance, your car’s mpg and the price per litre.
Result
Enter the distance, fuel economy and fuel price.
How it works
Litres used
miles ÷ mpg × 4.546
A UK gallon is 4.546 litres. For l/100 km: km × l/100 km ÷ 100.
Cost
litres × price per litre
Prices change daily, so this calculator uses the price you enter.
Want to convert mpg to litres per 100 km? Use the fuel economy converter.
Frequently asked questions
How do I work out fuel cost from mpg?
Divide the miles by your mpg to get gallons, multiply by 4.546 to get litres, then multiply by the price per litre. 120 miles at 45 mpg uses 12.1 litres; at 140p a litre that’s £16.97.
Why is my real mpg lower than the official figure?
Official figures come from standard lab tests. Short trips, cold weather, heavy loads, air conditioning and motorway speeds all use more fuel, so real-world economy is usually lower.
Does this work for an electric car?
No – it’s for petrol and diesel. For an EV, multiply the kWh used (miles ÷ miles per kWh) by your electricity price; the electricity cost calculator can help with the price part.
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