Fuel cost per mile calculator
Estimate UK fuel cost per mile from pump price and MPG, then project the fuel spend for a journey.
Formula: Cost Per Mile (pence) = (Fuel Price in p/L × 4.54609) ÷ UK Imperial MPG.
Pair the result with live station prices to judge whether a detour is worth it.
Frequently asked questions
What is the formula for fuel cost per mile in the UK?
The UK formula is: Cost Per Mile (pence) = (Fuel Price in pence per litre × 4.54609) ÷ UK MPG. Because UK fuel is sold in litres while fuel economy is measured in imperial gallons (4.54609 litres), multiplying by 4.54609 converts the litre price into a gallon price before dividing by miles per gallon.
What is the average cost of fuel per mile in the UK?
For a typical UK petrol car achieving 45 MPG at 142p per litre, the average fuel cost is 14.3p per mile (£14.35 per 100 miles). For a diesel car achieving 52 MPG at 148p per litre, the average fuel cost is 12.9p per mile (£12.94 per 100 miles).
Should I use petrol or diesel price?
Use the fuel type your vehicle actually burns (E10/E5 petrol or B7 diesel). Check live local pump prices on FuelRoute to use an accurate pence-per-litre figure.
Does this include wear and tear or HMRC mileage rates?
No. This calculator estimates fuel cost only. HMRC’s Approved Mileage Allowance Payment (AMAP) rate of 45p per mile for the first 10,000 business miles covers fuel plus insurance, servicing, road tax, and depreciation.
How does cost per mile help decide if a cheaper petrol station is worth the detour?
If your car costs 15p per mile in fuel, a 2-mile round-trip detour costs 30p in fuel. A 40-litre fill at a station 3p/L cheaper saves £1.20—giving a net saving of 90p. FuelRoute’s route planner automates this calculation.