Fuel Cost Calculator: Petrol, Diesel and CNG

How to use the fuel cost calculator

Enter how far you drive in a typical month, then your car's real-world mileage and the local fuel price. Add a second car to compare, for example the petrol and CNG versions of the same model, or a petrol SUV against a diesel one. The calculator shows the monthly and yearly cost and the cost per kilometre for each.

If you do not know your real mileage, measure it with a full-tank-to-full-tank test using our mileage calculator. Claimed figures from brochures are usually optimistic.

Making sense of the result

The per-kilometre figure is the most useful number. Petrol cars typically cost ₹5–8 per km, diesel ₹4.5–6 and CNG ₹3–4. An EV charged at home costs about ₹1–1.5 per km; compare that in the EV vs petrol calculator.

If Car B is cheaper to run but costs more to buy, divide the price difference by the monthly saving to see how many months it takes to pay back. Our petrol vs diesel vs CNG guide walks through this break-even maths, and our list of best mileage cars shows the most efficient options.

Frequently asked questions

How do I calculate monthly fuel cost?

Divide your monthly distance by your car’s real-world mileage to get litres (or kg for CNG), then multiply by the fuel price. For example, 1,200 km ÷ 16 km/l × ₹95 = ₹7,125.

Should I use claimed or real mileage?

Use real-world mileage. Claimed figures come from a lab test and are usually 20–35% higher than what you get in Indian traffic.

Is CNG always cheaper than petrol?

Per kilometre, yes, usually by 30–40%. But CNG cars cost more to buy, so they make financial sense mainly if you drive more than about 1,200 km a month.

Results are estimates for planning. Taxes, rates and prices vary by state, lender and dealer, so confirm final figures before you sign anything.