Fuel Cost Calculator
Work out the fuel cost of a journey based on distance, fuel efficiency, and pump price. Optionally compare two vehicles side-by-side.
Vehicle
+ Compare with a second vehicleSecond vehicle
MPG = miles per gallon. 1 UK gallon = 4.54609 litres. Check your manufacturer's claimed MPG or use a real-world figure (typically 10–20% lower).
Related: MPG Calculator · Fuel Efficiency · Trip Cost
How the Fuel Cost Calculator works
This calculator uses three inputs to estimate your journey's fuel cost: the distance in miles, your vehicle's fuel efficiency in MPG (miles per gallon), and the current pump price in pence per litre. It converts MPG to litres using the UK imperial gallon (4.54609 litres), calculates the fuel volume required, and multiplies by the price per litre to give a total cost in pounds.
For the most accurate results, use a real-world MPG figure rather than the manufacturer's official rating — real-world consumption is typically 10–20% higher. You can find your real-world MPG by filling your tank, noting the mileage, driving normally, then calculating miles ÷ gallons at your next fill. The optional vehicle comparison feature lets you see how much you could save by driving a more efficient car on the same route.
UK fuel prices change daily and vary by location — motorway services and rural stations often charge several pence more per litre than supermarket forecourts. Checking a price comparison app before filling up can reduce costs meaningfully over time, particularly for frequent or long-distance drivers.
Frequently asked questions
How do I calculate the cost of a journey by car?
To calculate a journey's fuel cost, divide the distance in miles by your car's MPG to get gallons used, multiply by 4.54609 to convert to litres, then multiply by the fuel price per litre. For example, a 100-mile trip in a car doing 40 MPG at 150p per litre costs (100 ÷ 40) × 4.54609 × £1.50 = approximately £17.05.
What is the average fuel price in the UK?
UK fuel prices fluctuate with global oil markets and duty. In recent years, petrol has typically ranged from around 140p to 190p per litre, while diesel has been slightly higher. The RAC and AA publish weekly UK pump price data. For the most accurate cost calculation, check your local forecourt price before travelling.
Does speed affect fuel consumption?
Yes, significantly. Most petrol and diesel cars are most efficient between 45 and 60 mph. Driving at 70 mph can use up to 9% more fuel than at 60 mph, and at 80 mph up to 25% more. Motorway driving at a steady speed is generally more efficient than stop-start urban driving, but high speeds increase aerodynamic drag and raise consumption considerably.
How can I reduce my fuel costs?
The most effective ways to cut fuel costs in the UK include driving at a steady, moderate speed; accelerating and braking smoothly; keeping tyres inflated to the correct pressure; removing roof racks and heavy items from the boot; and using air conditioning sparingly. Comparing fuel prices using apps like Petrol Prices or Waze can also save several pence per litre.