Fuel Cost Calculator
Estimate petrol, diesel or electric journey costs, see your cost per mile, and split the fare between passengers.
Calculate your journey fuel cost
Enter your distance, vehicle type and fuel or electricity price. Results update instantly as you change the numbers.
How to use this calculator
Start with the distance of your journey in miles. If you are driving there and back, switch on the return-trip option so the calculator doubles the mileage automatically.
For petrol or diesel, enter your car's MPG and the price per litre at your local forecourt. For an electric car, enter the car's efficiency in miles per kWh and your charging price. The calculator then shows the total cost, pence per mile, fuel or electricity used, and the cost per person if you are splitting the journey.
Petrol or diesel:
journey miles ÷ MPG × 4.54609 × fuel price per litre
Electric:
journey miles ÷ miles per kWh × electricity price per kWhThe result is an estimate, not a live quote. Real-world driving style, traffic, tyre pressure, weather, route type and vehicle load can all change the final cost.
What your result means
The headline figure is the estimated amount you will spend on fuel or electricity for the journey distance you entered. The cost per mile is often the most useful comparison number because it lets you compare different vehicles, routes and charging options more easily.
Compare car costs and cover
Your fuel cost is only one part of running a car. Insurance, breakdown cover, servicing, depreciation and finance can cost far more over a year.
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How fuel cost works
Fuel cost is driven by three numbers: the distance travelled, the vehicle's efficiency and the price of the energy used. A petrol or diesel car normally reports efficiency in miles per gallon. UK fuel, however, is bought in litres, so the calculation has to convert UK gallons into litres before multiplying by the pump price.
For example, a 100-mile journey in a 40 MPG petrol car uses 2.5 UK gallons. One UK gallon is 4.54609 litres, so the car uses about 11.37 litres. If petrol costs 155.5p per litre, the journey costs about £17.67 before parking, tolls or wear and tear.
Electric cars work differently. Instead of MPG, they use miles per kWh. If an EV averages 3.5 miles per kWh, a 100-mile journey uses about 28.57 kWh. At 26.11p per kWh, the same journey costs about £7.46. Public rapid charging can be much more expensive than home charging, so always use your real tariff where possible.
This calculator focuses on the direct energy cost of a journey. It does not include insurance, servicing, tyres, finance, depreciation, parking, tolls or congestion charges. For a fuller picture, use the commute and car running cost tools in this silo.
What affects your fuel cost
- Distance: longer journeys increase cost in a straight line.
- Fuel economy: better MPG or more miles per kWh lowers the cost per mile.
- Fuel price: local pump prices vary by area, brand and motorway services.
- Traffic and speed: stop-start driving and high motorway speeds can reduce efficiency.
- Vehicle load: passengers, luggage, roof boxes and towing can increase energy use.
- EV charging location: home charging is usually cheaper than public rapid charging.
Fuel cost calculator FAQs
How do I calculate fuel cost for a journey?
Divide your journey miles by your car's MPG, multiply by 4.54609 to convert UK gallons into litres, then multiply by the fuel price per litre. This calculator does that automatically.
How much does petrol cost per mile?
It depends on your MPG and the petrol price. A 40 MPG petrol car at 155.5p per litre costs about 17.7p per mile. A less efficient car costs more per mile.
How do I work out fuel cost from MPG?
MPG tells you how many miles your car travels per UK gallon. Because UK fuel is sold in litres, the calculation converts gallons into litres before applying the pump price.
Can this compare petrol, diesel and electric cars?
Yes. Petrol and diesel use MPG and price per litre. Electric vehicles use miles per kWh and electricity price per kWh, so the result is comparable as a cost per mile.
Are the fuel prices live?
No. The defaults are editable assumptions based on recent UK averages and energy price-cap data. Change them to match your local forecourt, home tariff or public charging rate.
Key terms used in this calculator
These plain-English glossary pages explain the main terms behind journey cost calculations.