Car & Vehicle

Mileage Comparison Calculator

Compare two vehicles on what they cost to run over the same distance, in whichever units each figure came in.

11 inputs Free, no sign-up

Your figures

Optional. It only affects how the result reads.

How much more the second option costs to buy or fit. Leave blank if there is no difference; fill it in to see how far you have to drive before the running-cost saving pays it back.

Try an example

Result

Your result

Enter your figures and the result appears here.

Estimates only. Rates, fees and specifications change. Confirm against the official source before you rely on a figure — see our disclaimer.

About this calculator

Two mileage figures are only comparable once they are in the same unit and priced at the same pump. This page does both: enter each vehicle's economy in whatever unit you have it in, and each one's fuel price, and the comparison is made per kilometre.

That matters when the two run on different fuels, when one figure came from a British review in mpg and the other from your own tank in km/L, or when you are weighing a more efficient vehicle that costs more to buy.

How to use this calculator

  1. Enter the distance you cover in a year.
  2. For each vehicle, enter its economy and pick the unit that figure is in.
  3. Enter the price of the fuel each one uses. If they use the same fuel, enter the same price twice.
  4. Name them if you like — it only changes how the result reads.
  5. If one costs more to buy, enter the difference to get a break-even distance.

The formula

Cost per km = Price per litre / Economy in km/L    (for each vehicle)
Yearly cost = Cost per km x Distance
Difference  = larger yearly cost - smaller

Any economy entered in L/100 km or mpg is converted to km/L first, through the reciprocal where the unit needs it. The comparison itself never happens in mixed units.

SymbolMeaningUnit
Distance Distance driven in a year km or mi
Economy What each vehicle returns any of the four
Price Fuel price for each vehicle ₹/L

Worked example

12,000 km a year; one car at 15 km/L on petrol at ₹105, another at 45 mpg imperial on diesel at ₹92:

45 mpg (imp) = 15.93 km/L
First  = 105 / 15    = 7.00 per km ->  84,000 a year
Second =  92 / 15.93 = 5.78 per km ->  69,323 a year
Difference = 14,677 a year

Notes and limits

  • Rated figures are comparable with rated figures and real figures with real ones. Comparing a brochure number against a measured one will flatter the brochure by 20–30%.
  • Fuel is not the whole running cost. Insurance, servicing, tyres and depreciation differ between vehicles too, sometimes by more than the fuel does — the car running cost calculator takes them.
  • A larger vehicle that suits your load is not badly chosen just because it costs more per kilometre. This page prices a comparison; it does not make the decision.
  • To compare an electric vehicle against a petrol one, use the EV vs petrol calculator, which works in kWh and allows for charging losses.

What this calculation assumes

  • Fuel only. Insurance, servicing, tyres and depreciation are not compared.
  • Both figures are ones you entered; no vehicle data is stored in this page.

Frequently asked questions

How do I compare two cars with mileage in different units?

Convert both to the same unit first, or let this page do it - each side has its own unit selector and the comparison is made in km/L internally. Comparing a km/L figure directly against an mpg one without converting is off by a factor of about 2.8.

Which vehicle is cheaper to run?

The one with the lower cost per kilometre, which is the fuel price divided by the economy. A vehicle with better mileage on a dearer fuel can easily lose to one with worse mileage on a cheaper fuel.

Does this include insurance and servicing?

No, fuel only. Those differ between vehicles as well and are often the larger part of the gap, so treat this as one component of the comparison rather than the whole of it.

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