Everyday Utilities
UK Fuel Cost Calculator
Fuel is one of the easiest trip costs to underestimate. Whether you are planning a motorway run, comparing MPG cars, or working out a week of commuting, a clear cost-per-mile figure helps you budget in pounds and pence.
This free UK fuel cost calculator uses miles, UK (imperial) MPG or L/100km, and the pump price per litre. Set multiple trips for a return journey or a working week. Everything runs in your browser — no account and no data stored.
Real economy depends on speed, traffic, weather and load. Treat results as planning estimates, not a guarantee of what the tank will cost.
Interactive tool
UK fuel · miles, MPG (imperial) or L/100km, £ per litre
One-way trip length in miles
UK miles per imperial gallon (common on UK dashboards)
e.g. 1.45 for 145p/L
Use 2 for a return journey, or 10 for a working week
Estimated fuel cost
Estimates only. Real economy varies with speed, load, weather and traffic. Does not include parking, congestion charge, insurance or wear and tear.
How to use this tool
- Choose MPG (UK) or L/100 km for your vehicle’s economy figure.
- Enter the trip distance in miles and your fuel economy.
- Enter the fuel price in pounds per litre (e.g. 1.45 for 145p).
- Set the number of trips if you need a return or multi-day total.
- Read total cost, litres used and cost per mile; copy results if useful.
MPG vs litres per 100 km
Many UK cars still show miles per gallon on the trip computer. That figure uses the imperial gallon (about 4.55 litres), not the US gallon. Official WLTP figures are often quoted in L/100km — lower is more efficient. This tool supports both so you can use whichever number you have.
Cost per mile is useful for splitting fuel with passengers or comparing a petrol car to public transport. For company mileage, HMRC has separate approved mileage allowance payments (AMAPs) that are not the same as your actual pump cost.
How the fuel maths works
With UK MPG: litres ≈ (miles ÷ MPG) × 4.54609, then multiply by £ per litre. With L/100km: convert miles to kilometres, then litres = (L/100km ÷ 100) × km. Multiplying by the number of trips scales both fuel and cost.