Free Fuel Cost Calculator

Our free fuel cost calculator works for petrol, diesel, and electric vehicles. Enter your vehicle's fuel efficiency (MPG or miles per kWh), the current fuel price, and your journey distance or annual mileage — and we'll instantly calculate your fuel cost per journey, per mile, and per year.

Finding Your Real-World MPG

The official WLTP (Worldwide Harmonised Light Vehicle Test Procedure) figure from your vehicle's brochure is the standard starting point — but real-world fuel economy is nearly always lower. Studies by fuel economy tracking services consistently show that real-world MPG averages around 10–20% below the WLTP figure, depending on vehicle type, driving style, and conditions.

To find your actual MPG:

• Check your trip computer — most modern cars display average fuel consumption in real time. Reset the counter at the start of a full tank for the most accurate reading.
• Calculate manually — fill the tank completely, note the odometer, drive normally, then fill again. Divide the miles driven by the litres used and multiply by 4.546 (litres per gallon) to get MPG.
• Check real-world reviews — sites like Honest John and Fuel Economy UK publish crowd-sourced real-world MPG figures for thousands of models.

For this calculator, use your real-world figure for accurate cost estimates, or use the official WLTP figure as an optimistic baseline.

Current UK Fuel Prices (2026)

UK fuel prices fluctuate continuously. As of May/June 2026, average pump prices are approximately:

• Unleaded petrol (E10): ~147–150p per litre
• Diesel (B7): ~153–157p per litre
• Home electricity (standard rate): ~24–25p per kWh
• EV off-peak / overnight tariff: ~7–10p per kWh
• Rapid public charging: ~60–85p per kWh

For live, up-to-date pump prices at stations near you, check the RAC Fuel Watch or Confused.com fuel price tracker.

Petrol vs Diesel — Which Is Cheaper to Run?

Diesel vehicles typically offer better fuel economy than equivalent petrol models — often by 10–20 MPG on motorway driving. However, the cost advantage depends on the price differential at the pump and how many miles you drive annually.

As a rule of thumb:

• If you drive under 10,000 miles/year predominantly in town, petrol is usually cheaper overall when you factor in the higher purchase price of diesel vehicles and Diesel Particulate Filter maintenance
• If you drive 10,000–20,000+ miles/year with significant motorway mileage, diesel usually wins on running cost per mile
• For high-mileage drivers doing 20,000+ miles/year, a hybrid or EV (if you can home-charge) typically beats both

Also factor in VED (road tax) — older diesel vehicles registered before April 2017 often face higher VED rates. Check with our Vehicle Tax Calculator.

Electric Vehicle Running Costs

EV running costs depend almost entirely on whether you can home-charge. Drivers on a dedicated overnight EV tariff (7–10p/kWh) can achieve the equivalent of approximately 2–3p per mile — compared to roughly 12–18p per mile for a petrol car. That's a saving of £1,000–£2,000+ per year at 12,000 miles.

However, public rapid charging (60–85p/kWh) is far more expensive — sometimes comparable to or more expensive than petrol per mile. EV economics depend heavily on your home-charging access and driving patterns.

Tips to Reduce Your Fuel Costs

• Keep tyres correctly inflated — under-inflated tyres increase rolling resistance and can reduce fuel economy by 1–3%
• Remove unnecessary weight — an extra 50kg reduces fuel economy by approximately 1–2%
• Plan routes to avoid stop-start traffic — urban driving with frequent braking and acceleration uses significantly more fuel than smooth motorway cruising
• Use cruise control on motorways — maintaining a constant speed dramatically improves efficiency compared to fluctuating speed
• Switch off at-idle accessories — air conditioning at low speeds can increase fuel consumption by 5–10%
• Keep the engine serviced — a poorly maintained engine (dirty air filter, worn spark plugs) can reduce MPG by up to 20%