EV vs Petrol Cost Calculator

About this calculator

An electric vehicle's running cost depends on where you charge it far more than on which car it is. A domestic tariff and a public fast charger can be four times apart, and that gap is larger than the difference between most pairs of cars.

This page asks for your tariff and your efficiency rather than assuming either. The comparison is made per kilometre, which is the only footing on which a litre of petrol and a kilowatt-hour of electricity can meet.

How to use this calculator

1. Enter how far you drive in a year.
2. Enter the petrol car's mileage and today's pump price.
3. Enter the EV's efficiency in kilometres per kWh. If your car shows Wh/km instead, divide 1,000 by it — 160 Wh/km is 6.25 km/kWh.
4. Enter the electricity rate you actually pay. Use your own bill for home charging, or the price on the charger for public use.
5. Add the price difference between the two cars, including a home charger if you need one.

The formula

Petrol per km   = Price per litre / km per litre
Electric per km = Price per kWh / km per kWh
Yearly cost     = Cost per km x Distance
Break-even km   = Extra up-front cost / (difference in cost per km)

The efficiency from a car's trip computer counts energy leaving the battery, not energy leaving the socket. Charging losses of 10–15% sit between the two, so the real cost is a little above this figure — the EV charging cost calculator accounts for them explicitly.

Worked example

15,000 km a year; petrol 15 km/L at ₹105, EV 6 km/kWh at ₹8 a unit; EV ₹5,00,000 dearer:

Petrol   = 105 / 15 = 7.00 per km -> 1,05,000 a year
Electric =   8 /  6 = 1.33 per km ->   20,000 a year
Saving   = 85,000 a year
Break-even = 5,00,000 / 5.67 = 88,235 km

Just under six years at that distance — and considerably longer if the charging is done at public rates.

Notes and limits

• Charge at home on a domestic tariff and the gap is large. Charge mostly at public fast chargers and it narrows sharply, sometimes to nothing.
• An EV's efficiency swings more with speed and temperature than a petrol car's mileage does. Winter highway running can use half again what mild city running does.
• Servicing is generally cheaper on an electric vehicle — no oil, fewer moving parts, less brake wear from regeneration. None of that is in this comparison.
• Battery replacement is a real long-term cost and an uncertain one. It is not included here because nobody can put an honest figure on it for a specific car.
• Resale values for electric vehicles in India are still establishing themselves. Treat a break-even six years out with appropriate caution.

What this calculation assumes

• Energy cost only. Servicing, insurance, battery replacement and resale are not compared.
• Charging losses are not included - the efficiency entered is taken as energy per kilometre at the battery.
• The tariff entered applies to all the charging, which is rarely exactly true if you use public chargers.