Journey Fuel Cost Calculator
Calculate fuel required and journey fuel cost from distance, fuel economy and fuel price.
What this tool calculates
Journey Fuel Cost Calculator is designed to give a direct answer from the values entered above. The main inputs on this page are Distance (miles), Fuel economy (UK mpg), Fuel price (£ per litre). The result is intended to be readable immediately, with the explanation below available when you need to verify the method.
Method and calculation basis
For UK MPG, litres used = miles ÷ MPG × 4.54609. Cost is litres × price per litre. UK imperial gallons are not the same size as US gallons.
Worked examples
100 miles at 40 UK MPG
Fuel ≈ 11.37 litres. At £1.45/litre, cost is about £16.49.
Compare two vehicles
Use the same mileage and fuel price for both so MPG is the changing variable.
Understanding the result
The output should be read in the units shown beside the result. If you are comparing alternatives, keep all unchanged assumptions identical and alter one input at a time. That makes it easier to see which value is responsible for the difference.
Assumptions, edge cases and accuracy
Prices, tax treatment and statutory rules can change. Where the tool relates to tax or payroll, verify the applicable tax year and current official guidance before making a financial decision.
Sources and methodology
- HM Revenue & Customs (HMRC) — Current UK tax and VAT rules where applicable
- UK Government / GOV.UK — Statutory rates and official guidance
Method reviewed for Instant Solvers V10.0 · October 2026. If you find a calculation or explanation that needs correcting, use the site Contact page and include the tool URL and the values you entered.