How the mileage figures are worked out

The short version

1. Published mileage: the company's ARAI-certified figure, or a road-test figure where none is published.
2. Driving condition: scaled to city, mixed or highway driving.
3. Load: optionally reduced for a full car with the AC on.
4. Fuel blend: for petrol, adjusted for the ethanol in the fuel.

The result is labelled an estimate wherever it appears. Nobody at calculatemileage drove the car.

1. What ARAI mileage means

ARAI mileage is measured in a laboratory on a fixed driving cycle, on fuel with 10% ethanol. Every car runs the same cycle, so the figure is good for comparing cars with each other. It is one combined number and it is higher than what most people get on the road, because the test has no traffic, no passengers and no air conditioning.

Some models have no published ARAI figure. For those the site uses a figure measured on a road test by Autocar India, or the owner-reported figure Autocar lists, and the car page labels it as such. A driven figure is never shown as an ARAI rating.

2. City, mixed and highway estimates

There is no official city or highway figure, so the site derives them from the rating with these factors. They are assumptions, set to reflect the usual gap between lab and road, not measured for each car.

A road-test figure was already driven on a real road, so it is treated as the mixed figure and city and highway are scaled from it by the ratio between the factors. Scaling it down again would count the road twice.

3. Load and air conditioning

"1 or 2 people" uses the estimate as it is. "Full car + AC" takes a further 10% off. This is also an assumption, a single figure for extra weight and the compressor running together.

4. Fuel blend and E20

The Ministry of Petroleum and Natural Gas requires oil companies to sell E20 petrol at filling stations across India from 1 April 2026. (ETV Bharat, 28 Feb 2026). Ethanol carries less energy per litre than petrol, so a higher blend gives fewer kilometres per litre.

ARAI laboratory tests on validated vehicles put the fuel efficiency drop with E20 at 2% to 6%. (Press Information Bureau (ARAI press conference), 4 Jul 2026). The site uses 0.4% less mileage for each percent of ethanol, which puts E20 at about 4% below the E10 the rating was measured on, the middle of that range. A car engineered for E20 is assumed to lose half as much. Picking a single figure inside a published range is an assumption.

A worked example

A petrol car rated at 20 kmpl, built for E10:

What the method does not account for

• How you drive: hard acceleration and high speed cost more than any factor here.
• Traffic, terrain, weather and temperature on your actual route.
• Tyre pressure, servicing and the age of the car.
• Fuel quality beyond its ethanol content.
• Differences between cars with the same rating; every car on an engine and gearbox gets the same factors.

How to read the numbers

Use them to compare cars and to plan running costs. Treat a single figure as the middle of a range, not a promise. For your own car, measure it with the full tank method on the mileage calculator; that beats any estimate.

Where the data comes from

Ratings, variants and ex-showroom prices for 113 models are collected from public listings (ZigWheels, CarDekho, Autocar India). Each car page names its sources and the date they were collected. Prices are ex-showroom as listed on that date and vary by city.

Update and source policy

• A figure is shown only if a source publishes it. Gaps stay gaps rather than being filled with a guess.
• A road-test or owner figure is always labelled as one, never as an ARAI rating.
• Collection dates on car pages change only when the data is collected again.
• When any factor on this page changes, the method version goes up and the change is listed below.

Version history