myFuel Cost Calculator
Calculate your annual, monthly and per-trip fuel spend — and see how much you could save with a more efficient car.
About the Fuel Cost Calculator
This calculator shows exactly what you spend on fuel — annually, monthly, weekly, and per trip. Enter your annual mileage, fuel efficiency and local fuel price to get an instant breakdown. The optional comparison section lets you see how much you would save by switching to a more efficient car or a different fuel type.
How is fuel cost calculated?
In metric: annual distance (km) ÷ 100 × efficiency (L/100km) × fuel price ($/L) = annual cost. In imperial: annual distance (miles) ÷ MPG × fuel price ($/gallon) = annual cost. The calculator divides by 12 for monthly and 52 for weekly figures.
Metric vs imperial
Toggle between metric (kilometres, litres, L/100km) and imperial (miles, gallons, MPG) using the buttons at the top. Note that MPG figures differ between the US (US gallons, 3.785 L) and the UK (imperial gallons, 4.546 L) — this calculator uses US gallons in imperial mode.
Efficiency comparison
The optional comparison section lets you enter a different efficiency figure — useful when you are comparing two cars, considering an upgrade, or wondering how much an electric vehicle would save on running costs versus petrol.
Fuel prices and price comparison
UK pump prices vary by 5-15p/litre between the cheapest supermarket forecourts and motorway services. Supermarket fuel (Tesco, Asda, Sainsbury's, Morrisons) is typically 3-7p/litre cheaper than branded forecourts. Motorway services are usually the most expensive. The PetrolPrices.com database tracks live prices at over 8,000 UK stations.
- Supermarket forecourts — typically 3-7p/litre cheaper than branded stations; Asda often lowest
- Motorway services — typically 10-20p/litre more than local prices; fill up before motorway if possible
- Fuel cards — business drivers can get wholesale pricing via fuel cards, saving 3-8p/litre
- Timing — prices tend to be lowest mid-week (Tuesday/Wednesday) when demand is lower
How to reduce fuel costs
Beyond choosing a fuel-efficient car, driving style accounts for 20-30% of real-world fuel consumption differences between drivers. Smooth acceleration, anticipating stops to coast rather than brake, maintaining motorway speeds around 60-65 mph, and keeping tyres at correct pressure are the highest-impact adjustments.
- Eco driving — smooth acceleration and deceleration can improve economy by 10-20%
- Tyre pressure — correctly inflated tyres reduce rolling resistance; check monthly
- Weight — remove unnecessary weight from the boot; an extra 50kg reduces economy by about 2%
- Air conditioning — uses 5-10% more fuel in town; use ventilation at speeds below 40 mph and AC above 60 mph where drag from open windows costs more