Petrol Expense Calculator
Calculate your monthly and annual petrol cost from distance driven and mileage.
Your inputs
Uses your vehicle's actual mileage rather than the manufacturer-claimed figure for a realistic estimate — real-world mileage is usually lower.
Estimates only. Figures are indicative and do not constitute financial advice.
About the Petrol Expense Calculator
"Petrol cost calculator," "monthly fuel cost calculator," or "petrol expense per month" is one of those searches everyone types after a fuel price hike, or when trying to budget a new commute — you know roughly how far you drive, but converting that into a real monthly rupee figure takes a second to do properly. This calculator does exactly that: enter your monthly distance, your vehicle's actual mileage, and the current petrol price, and get your monthly and annual fuel cost instantly.
The formula is straightforward — distance divided by mileage gives you litres needed, multiplied by the price per litre gives you cost — but the number that actually matters is using your real observed mileage, not the ARAI-certified figure printed in brochures, which is almost always higher than what you get in real city or highway driving. It's also worth knowing that most petrol sold in India today is blended with ethanol (up to 20% under the E20 programme) rather than being pure petrol, which has a small effect on real-world mileage compared to older, unblended-fuel-era brochure figures — one more reason your actual observed mileage is more reliable than any printed number. This calculator also shows your cost per kilometre, a genuinely useful number when comparing a petrol vehicle against a diesel or CNG alternative, or when deciding whether a longer commute for a new job is actually affordable. Run it whenever petrol prices change in your city to keep your monthly fuel budget realistic, or use it to compare two vehicles with different mileage figures side by side.
How to use this calculator
- Enter your monthly distance driven.
- Enter your vehicle's actual mileage (km per litre).
- Enter the current petrol price per litre.
- See your monthly and annual petrol cost, and cost per km.
Frequently asked questions
›How do I find my car's actual mileage?
Fill your tank completely, reset your trip meter, drive normally until you need to refuel, then divide the distance covered by the litres needed to refill — this gives your real-world mileage, usually lower than the brochure figure.
›Why is my real mileage lower than the advertised figure?
Advertised (ARAI-certified) mileage is measured under controlled test conditions; real-world factors like traffic, AC usage, and driving style typically reduce it by 15-25%.
›How often do petrol prices change in India?
Petrol and diesel prices in India are revised daily based on international crude oil prices and currency exchange rates, though changes on any given day are usually small.
›Does this calculator account for CNG or electric vehicles?
No, this is specifically for petrol vehicles — the cost-per-km figure here is useful for comparing against a CNG or EV's running cost if you know their respective figures separately.
›Does ethanol-blended petrol affect my mileage?
Most petrol sold in India is now blended with ethanol (up to 20% under the E20 programme), which typically results in slightly lower mileage per litre compared to pure petrol — another reason to rely on your own observed mileage rather than an old or brochure figure.
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Read the full guide
How Much Petrol Is Actually Costing You Every Month