PetrolCalculator

Fuel calculator

Fuel Price Break-even Calculator

Check whether a lower pump price still saves money after the extra round-trip drive.

Use this calculator

Enter the fuel prices, extra round-trip distance and purchase amount.

What your result means

Gross pump saving is £4.00 before the detour. The 4-mile extra round trip costs £0.57, leaving about £3.43. The saving reaches zero at roughly 28.3 extra round-trip miles.

Worked example

Example values are illustrative and editable in the calculator.

Gross pump saving
£4.00
Extra driving cost
£0.57

The example nets £3.43.

Formula

Net saving=Gross pump saving−Extra driving cost\text{Net saving}=\text{Gross pump saving}-\text{Extra driving cost}

Extra round-trip distance sensitivity

Extra distanceExtra driving costNet saving
0 miles£0.00£4.00
5 miles£0.71£3.29
10 miles£1.41£2.59
20 miles£2.83£1.17
28.3 miles£4.00£0.00

When is the cheaper station not worth it?

A small pump-price difference, a small purchase, a long detour or lower MPG can remove the saving. If the extra drive exceeds the break-even distance, the detour costs more overall.

Assumptions and limitations

  • Extra distance means total additional round-trip miles.
  • The entered litres are bought at the cheaper station.
  • Extra driving is costed at the cheaper-station price. Time and vehicle wear are excluded.

Helpful questions

Does extra distance include the return trip?

Yes. Enter the total additional round-trip distance.

What if I buy only part of a tank?

Enter the actual litres you expect to purchase.

Does this include the value of my time?

No. It compares fuel costs only.

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