PetrolCalculator

Fuel calculator

Petrol vs Diesel Calculator

Compare entered petrol and diesel costs for the same journey.

Use this calculator

Petrol

Diesel

Enter petrol and diesel assumptions for the same journey.

What your result means

This compares petrol and diesel fuel cost for the same journey using the prices and UK MPG entered. It does not claim either fuel is universally cheaper.

Worked comparison

Using 250 miles, petrol at 142p/litre and 45 UK MPG, and diesel at 150p/litre and 50 UK MPG:

Petrol
25.3 litres · £35.86
Diesel
22.7 litres · £34.10
Difference
£1.77

Diesel is lower for these assumptions only.

Formula

Cost=Journey milesUK MPG×4.54609×Price (£/litre)\text{Cost}=\frac{\text{Journey miles}}{\text{UK MPG}}\times4.54609\times\text{Price (£/litre)}

Illustrative same-journey comparison

FuelLitresJourney cost
Petrol25.3 litres£35.86
Diesel22.7 litres£34.10

Helpful questions

Is diesel always cheaper than petrol?

No. The result depends on the fuel prices and MPG values entered for the same journey.

Why compare the same journey?

Using one distance makes the difference reflect the entered fuel price and efficiency assumptions rather than different journeys.

Does this include all motoring costs?

No. It compares fuel cost only, not purchase price, insurance, tax, servicing or depreciation.

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