UtiliMate

Free browser tool

Fuel Cost Calculator

Use the units your vehicle and fuel receipt actually show. Estimate a complete trip in miles or kilometres, with UK/US MPG or litres per 100 km.

Estimate the whole trip

Changing a unit converts a valid entered number automatically. Recalculate after any change. Include both legs in the distance for a return trip.

Currency labels the entered price and result; it does not convert money.

Enter your values, then calculate.

Inputs stay in this browser. We record only an anonymous “tool used” event, never your values.

How it works

For L/100 km, litres used = kilometres ÷ 100 × consumption. For MPG, gallons used = miles ÷ MPG using the selected UK or US gallon. Fuel cost = litres used × price per litre after converting your chosen price unit. Calculations use unrounded conversions; the total display rounds to two currency decimal places.

MPG is miles per gallon, but UK imperial and US liquid gallons are different sizes. Select the convention shown by your vehicle; currency does not determine it. Price units are selected separately.

We use 1 mile = 1.609344 km, 1 UK imperial gallon = 4.54609 litres, and 1 US liquid gallon = 3.785411784 litres. NIST conversion factors distinguish the two gallons; NIST's volume table gives the US liquid-gallon factor.

A worked UK example

For an illustrative 200-mile total trip at 50 MPG (UK imperial), fuel use is 4 imperial gallons, or 18.18436 litres. At an entered £1.45 per litre, the estimated fuel cost is £26.37. These are example inputs, not current pump prices or a promise of real-world consumption.

Three practical tips

  • Use recent real-world consumption, not only the brochure figure.
  • Allow for traffic, weather, load and elevation.
  • For a return trip, include the complete distance.

Are UK MPG and US MPG interchangeable?

No. UK MPG uses an imperial gallon; US MPG uses a smaller US liquid gallon. Select the vehicle’s stated convention separately from your fuel-price unit. A price in GBP does not establish which MPG convention applies.