Fuel Cost Calculator UK
Work out exactly what your next drive will cost in petrol or diesel. Enter the distance in miles, your car's MPG and the price per litre and the calculator returns the fuel cost for that journey in seconds. It uses the UK gallon (4.546 litres) and pence per litre, so the figure you see matches the price on the forecourt and the MPG in your handbook.
Useful for the daily commute, a holiday road trip, a house move, a weekly mileage estimate or a one-off run up the M1. You can switch between one-way and return trips and try different fuel prices to see how a 5p swing at the pump changes your monthly spend.
Ready to Calculate
Enter your journey details to see the fuel cost breakdown.
How the Fuel Cost Calculator Works
The maths behind the calculator is the same formula HMRC and the AA use:
Fuel cost = (Distance ÷ MPG) × 4.546 × Price per litre
Three numbers, one answer. Distance gives you the gallons you'll burn, multiplying by 4.546 turns those gallons into litres, and multiplying by price per litre gives you the cash figure.
You can also flip it to find your cost per mile, which is the most honest number for comparing two cars or two routes.
Cost per mile = (Price per litre × 4.546) ÷ MPG
A car doing 45 MPG with petrol at 157p comes out at roughly 15.9p a mile. The same car on a tank of diesel at 189p with 55 MPG sits at about 15.6p a mile. Close on paper, but the diesel pulls ahead the more miles you do per year.
How to Use It
Enter Distance
Enter the distance in miles. If you don't know it, run the postcodes through Google Maps or the AA route planner.
Pick Fuel Type
Petrol (E10), super unleaded, diesel (B7) or LPG.
Enter Price
Enter the price per litre in pence. You'll see this on the forecourt board or on PetrolPrices.
Add MPG
Use the trip computer reading rather than the brochure number if you have it.
The result shows the total fuel cost, the litres you'll use and the cost per mile.
Current UK Fuel Prices
Average pump prices for May 2026:
Unleaded (E10)
~157p
Diesel (B7)
~189p
Super Unleaded
+8–12p
above standard
Prices spiked in March 2026 after the Middle East conflict pushed Brent crude above $85 a barrel, with petrol up around 12p and diesel up around 25p per litre in the three weeks that followed. The gap between petrol and diesel has stayed wider than the 2025 average of 7.5p, sitting closer to 18p in spring 2026.
What You're Actually Paying For at the Pump
Based on the DESNZ March 2026 breakdown for petrol:
Wholesale, distribution and retailer margin
64p
Fuel duty (frozen since 2022)
52.95p
VAT at 20%
23p
Total Estimate
~140p
Fuel duty is a flat amount per litre. VAT is then charged on top of duty plus the basic price, so when wholesale rises, the VAT you pay rises with it. That's why a 5p wholesale increase usually shows up as 6p at the pump.
Worked Examples
100-mile trip, petrol car at 45 MPG, 157p/litre: £15.86
Manchester to London (400 round trip), diesel at 55 MPG, 189p/litre: £62.51
Daily 30-mile commute, petrol car at 40 MPG, 157p/litre: £5.35 a day (£107/month)
10,000 miles a year, petrol car at 45 MPG, 157p/litre: £1,586 a year
How Much Petrol Per Mile in the UK?
For an average petrol car doing 40–50 MPG at 157p per litre, expect 14p to 17p per mile.
| Vehicle Setup | Cost Per Mile |
|---|---|
| 30 MPG Petrol | 23.8p |
| 40 MPG Petrol | 17.8p |
| 50 MPG Petrol | 14.3p |
| 60 MPG Petrol | 11.9p |
| 50 MPG Diesel | 17.2p |
| 60 MPG Diesel | 14.3p |
Fuel Cost Calculator by Reg
If you're trying to find your car's official MPG by registration, the Vehicle Certification Agency (VCA) runs a free lookup at vehicle-certification-agency.gov.uk that returns the WLTP combined figure for any UK-registered car. Plug that figure into this calculator for an estimate, then adjust down by 15–20% to match real-world driving.
The DVLA vehicle enquiry service confirms tax and MOT status but doesn't return MPG, so the VCA database is the one you want.
Petrol vs Diesel: Which Is Cheaper to Run?
Diesel Wins
Regularly drive 12,000+ miles a year, mostly motorways. 15–25% better economy beats the higher pump price over time.
Petrol Wins
Under 10,000 miles a year, urban commuters, short trips. Cheaper at pump and less risk of DPF clogs.
Hybrid Wins
Stop-start city traffic. Self-charging hybrids hit 60+ MPG in town where petrol drops to 30.
How to Cut Your Fuel Bill
Drive between 50 and 60 mph on the motorway where safe.
Check tyre pressures monthly to save up to 5% in MPG.
Lose the roof box and extra weight in the boot.
Combine errands into one trip to avoid cold engine burn.
Use supermarkets for cheaper fuel (avg 4.6p less).
Smooth braking and gentle acceleration save 20-30%.
Frequently Asked Questions
Scientific References
- UK Department for Energy Security and Net Zero. Quarterly Energy Prices, March 2026. GOV.UK.
- House of Commons Library. Petrol and diesel prices, briefing SN04712. Updated March 2026.
- RAC Fuel Watch. Latest UK petrol and diesel prices. RAC Drive.
- PetrolPrices.co.uk. UK Fuel Price Index, weekly DESNZ averages. April 2026.
- Office for National Statistics. Average retail prices: motor fuels, series CZMK. April 2026.
- Competition and Markets Authority. Road Fuel Prices Scheme and Fuel Finder Scheme. February 2026.
- Vehicle Certification Agency. Official Fuel Consumption and CO2 Figures. vehicle-certification-agency.gov.uk.
- HMRC. Fuel duty rates: hydrocarbon oils bulletin. GOV.UK.