Diesel journey cost

Work out the fuel cost of a diesel journey from the distance, your car's fuel economy and the price at the pump.

Journey distance (miles)Fuel economy (mpg)Diesel price (£/L)

Result

Fuel used

Cost

How to use this tool

Enter the journey distance in miles.
Enter your car's fuel economy in mpg (UK gallons).
Enter the diesel price per litre you want to use; the calculator does not fetch live pump prices.
Read the fuel used and total cost.

Uses UK imperial gallons (4.54609 litres), not US gallons.
Uses the diesel price you enter; it does not fetch live pump prices.
Diesel engines typically return higher mpg than equivalent petrol engines, especially on motorway journeys — use your car's actual figure.

Technical details: what the fields mean

Journey distance distanceMiles: Total journey distance, in miles.
Fuel economy mpg: Miles per UK gallon — use your car's real-world average rather than the official spec figure.
Diesel price pricePerLitre: Diesel price you entered, in pounds per litre; no live price feed is used.

Methodology

Litres used = (distance ÷ mpg) × 4.54609 (litres per UK gallon). Cost = litres used × price per litre.

Worked example

200 mile journey, 55mpg, £1.50/litre

Inputs: Journey distance: 200 miles, Fuel economy: 55 mpg, Diesel price: £1.50/L

Result: 16.5 litres, £24.80

Practical guidance

Diesel typically shows its efficiency advantage most on long, steady motorway journeys rather than short urban trips.
Compare to the petrol journey cost calculator using the same distance for a direct comparison.

Common mistakes

Using a US gallon figure instead of a UK gallon.
Assuming diesel is always cheaper per mile without checking the current diesel-vs-petrol price gap, which changes over time.

At 55mpg and £1.50/litre, about £24.80.

Last reviewed: 2026-10-11

Real-world fuel economy varies with driving style, load and conditions — treat this as an estimate.

This tool provides an indicative estimate, based on the assumptions stated above.

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