1. Convert miles and MPG to litres
Litres used = journey miles ÷ UK MPG × 4.54609. A UK gallon contains 4.54609 litres, which is different from a US gallon.
Journey cost calculator for petrol and diesel
How much will your UK journey cost in fuel? Enter a route or mileage, your fuel economy and pump price. Estimate litres used, one-way and return fuel costs, cost per mile and the cost per person.
Filling up instead? Estimate the cost of a full tank or top-up.
Your route will appear here
Enter your start and destination, then select Calculate journey cost.
Loading your route map. Your journey estimate is available alongside it.
Calculate the journey cost. Then compare places to fill up.
This calculator estimates fuel costs from your route or mileage, MPG and price per litre. To compare actual stations, use our free fuel route planner: it checks listed prices and estimates the saving after extra driving. The app adds saved vehicles, fill-up history and live traffic features, with access depending on your plan and allowances.
How to calculate fuel cost for a journey
The calculator uses UK imperial gallons and a road-distance estimate, so the result is more useful than multiplying a straight-line distance by a rough cost per mile.
2. Apply the fuel price
Journey cost = litres used × price per litre. If the pump price is entered in pence, divide it by 100 before multiplying.
3. Add the journey options
Select a return journey to double the one-way distance, or split the result between passengers. The cheaper-station option also subtracts the fuel used over a detour.
What does 100 miles cost at 45 UK MPG?
A 100-mile journey at 45 UK MPG uses about 10.10 litres. At 150p per litre, the estimated one-way fuel cost is £15.15. Real consumption can differ with traffic, weather, load and driving style, so treat the result as an estimate.
Fuel cost calculator questions
How do I calculate fuel cost for a journey?
Divide journey miles by UK MPG, multiply by 4.54609 to get litres used, then multiply litres by the fuel price per litre. This calculator performs those steps using an estimated road route or a distance you enter.
Why does the calculator ask for UK MPG?
A UK imperial gallon is 4.54609 litres, so UK MPG and US MPG produce different answers. Use the UK MPG figure for your vehicle, or switch the calculator to litres per 100km.
Can I calculate a return journey or cost per person?
Yes. Select Return journey to double the one-way route and Split the cost to show an estimated cost per passenger.
Does cheaper petrol still save money after a detour?
Not always. Compare the pump-price saving with fuel used over the extra miles. The optional cheaper-station comparison lets you enter a price and detour to estimate the saving. To find and compare actual stations, use the separate fuel route planner on this website.
Keep your vehicle, journeys and fill-ups together.
Compare station prices and detour savings in the website route planner. Keep vehicles, journeys and fill-ups in the app, with live traffic checks according to your plan and allowance.
