Car & Vehicle

Mileage Calculator

Measure the mileage your vehicle actually returns from one tank, in km/L, L/100 km and mpg.

6 inputs Free, no sign-up

Your figures

Trip meter reading between the two fill-ups, or the difference on the odometer.

What went in at the second fill-up. That is the amount the trip used, which is why the tank has to be filled to the same point both times.

All four are shown whichever you pick. This one leads.

The price you actually paid. Pump prices move daily and differ by several rupees between states, so the round number here is a placeholder, not a quote.

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

The mileage figure that matters is the one your vehicle actually returns, not the one on the brochure. Measuring it takes two fill-ups and a trip meter: fill the tank, drive normally, fill it again, and divide the distance by what went in.

The result is shown in all four units at once, because the same car reads 14 km/L, 7.14 L/100 km, 32.9 mpg on a US gallon and 39.5 mpg on an imperial one — four numbers describing one tank.

How to use this calculator

  1. Fill the tank completely and reset the trip meter.
  2. Drive normally until the tank is at least half used — a longer run gives a better figure.
  3. Fill the tank completely again and note how many litres it took.
  4. Enter the trip distance and the litres. Add the fuel price if you also want the running cost.

Use the same pump and the same automatic cut-off both times. Topping up past the cut-off is the main source of error in this measurement.

The formula

Mileage     = Distance / Fuel used
L/100 km    = 100 / Mileage
mpg (US)    = Mileage x 3.785411784 / 1.609344
mpg (imp)   = Mileage x 4.54609 / 1.609344
Cost per km = Fuel price / Mileage

Indian vehicles are rated in kilometres per litre, where a higher number is better. Much of the world uses litres per 100 kilometres, where a lower number is better. Going between the two is a reciprocal, not a scale factor, which is why 20 km/L is 5 L/100 km rather than anything that looks like 20 multiplied by something.

SymbolMeaningUnit
Distance Distance covered between fill-ups km or mi
Fuel used Fuel added to refill the tank L or gal

Worked example

420 km covered on 30 litres:

Mileage   = 420 / 30   = 14 km/L
L/100 km  = 100 / 14   = 7.14
mpg (imp) = 14 x 2.825 = 39.55

With petrol at ₹105 a litre, that is ₹7.50 per kilometre, or ₹750 per 100 kilometres.

Notes and limits

  • One tank is a sample, not a measurement. Three or four consecutive tanks give a figure you can rely on.
  • Air conditioning, load, tyre pressure and traffic all move mileage by more than most people expect. A city tank and a highway tank are different numbers.
  • Manufacturer figures come from a standardised test and are normally 20–30% above real-world city driving. A gap is expected, not a fault.
  • For CNG, enter kilograms in place of litres; the result reads as km/kg.
  • "mpg" on its own is ambiguous by about 20%, because a US gallon is 3.785 litres and an imperial gallon is 4.546. Both are shown, and both are labelled.

What this calculation assumes

  • The tank was filled to the same level before and after.
  • The distance covers exactly the fuel measured.
  • The result is the measurement you supplied, not a rating for the vehicle.

Frequently asked questions

How do I calculate my real mileage?

Fill the tank, reset the trip meter, drive normally, then fill again and note the litres. Divide the trip distance by the litres. Use the same pump and the same automatic cut-off both times.

Why is my mileage lower than the rated figure?

Rated figures come from a controlled test cycle with no traffic, no air conditioning and a light load. Real city driving is typically 20-30% below it. A gap of that size is normal.

How many tanks should I measure?

At least three. A single tank is affected by the route, traffic and how precisely the tank was filled. Averaging three or four consecutive tanks removes most of that noise.

Is 14 km/L the same as 39 mpg?

On an imperial gallon, yes - 14 km/L is 39.55 mpg. On a US gallon it is 32.93 mpg. The two gallons differ by 20%, so a figure quoted as "mpg" with no gallon named cannot be compared with anything.

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