Fuel Cost Calculator UK
Calculate the fuel needed and total cost for a trip from distance, mileage and fuel price.
How it works
A discount reduces the original price by a percentage. The saving is the price times the discount; the sale price is what remains.
Sale price = Price × (1 − discount%)Frequently asked questions
How do I calculate fuel cost for a trip?
Work out litres used (distance ÷ mpg × 4.546), then multiply by the price per litre. 300 miles at 45 mpg and £1.40/litre is about £42.40.
Why convert between mpg and litres?
UK economy is quoted in miles per gallon but fuel is sold per litre, so you convert using 4.546 litres per imperial gallon.
How many litres are in a UK gallon?
An imperial gallon is about 4.546 litres — larger than the US gallon of 3.785 litres.
Does town or motorway driving cost more?
Town driving usually returns lower mpg due to stop-start traffic, so it costs more per mile than steady motorway driving.
What raises my fuel consumption?
Heavy loads, roof boxes, aggressive acceleration, high speeds and under-inflated tyres all increase fuel use and cost.
How do I split fuel costs?
Calculate the total trip fuel cost and divide it by the number of people sharing the journey.
Estimating the fuel cost of a trip
The fuel cost of a journey depends on the distance, your car’s fuel economy in miles per gallon (mpg), and the pump price per litre. In the UK fuel is sold in litres but economy is quoted in mpg, so the calculation converts between the two.
The calculation
Litres used = distance ÷ mpg × 4.546 (litres per imperial gallon), then multiply by the price per litre. For a 300-mile trip at 45 mpg with petrol at £1.40 a litre: 300 ÷ 45 × 4.546 ≈ 30.3 litres, costing about £42.40.
What changes the cost
Motorway cruising usually returns better mpg than stop-start town driving, so real economy can differ from the official figure. Heavy loads, roof boxes, hard acceleration and under-inflated tyres all raise consumption and cost.
For a return trip, double the distance; to share a journey, divide the total cost by the number of passengers. Diesel and petrol prices differ, so use the correct pump price for your vehicle.
Results are estimates for general guidance in United Kingdom and may not reflect the latest local rates, fees or rules. Check official sources before making decisions.