Fuel Cost Calculator
Enter the journey distance, your car's fuel economy (mpg) and the price per litre to see the journey's fuel cost, your cost per mile and an optional per-person split.
How it works
Cost = distance ÷ mpg × 4.546 × price per litre (4.546 converts gallons to litres). A 200-mile trip at 45 mpg and £1.45/litre costs about £29.30.
Real-world economy differs from official figures — motorway speed, town driving, load and air-con all move mpg by 10-30%. Measure your true mpg brim-to-brim for accurate budgeting.
For business mileage, remember HMRC's approved rate (55p/25p per mile in 2026/27) covers fuel AND wear — your pure fuel cost per mile is usually well below it, which is what makes claiming worthwhile.
FAQ
How do I calculate fuel cost for a journey?
Divide miles by your mpg to get gallons, multiply by 4.546 to get litres, then by the pump price: 200 miles ÷ 45 mpg × 4.546 × £1.45 ≈ £29.30. Add tolls and parking separately, and double the distance for a return trip.
What is my fuel cost per mile?
Roughly 4.546 × price per litre ÷ mpg: at 45 mpg and £1.45/litre that is about 14.6p per mile. Compare that with HMRC's 55p approved mileage rate and you can see how much of the allowance covers wear, insurance and depreciation rather than fuel.
How can I improve my car's mpg?
Smooth acceleration, keeping to ~60-65 mph on motorways, correct tyre pressures, removing roof boxes and shedding boot weight each add a few percent — together often 15-20%. Short cold-engine trips are the biggest economy killer; combining errands into one run genuinely saves fuel.