How long will your EV need at a wall box or a public charger, and what will the session cost? Enter battery size, charger power and the charge levels you want, and you get the time and the bill in seconds.
How the calculation works
Energy added equals battery size times (target % minus current %) divided by 100. Energy drawn from the supply is the energy added divided by charging efficiency. Time is the energy drawn divided by charger power, and cost is the energy drawn multiplied by your electricity rate.
Worked example
A 40 kWh battery charged from 20% to 80% adds 24 kWh. At 90% efficiency the supply provides about 26.7 kWh. On a 7.4 kW home charger that takes about 3 h 36 min and costs about ₹213 at ₹8 per kWh.
Frequently asked questions
Why is charging slower above 80%?
Most batteries reduce charging power as they fill up to protect the cells, so the last 20% takes disproportionately longer on DC fast chargers. This calculator assumes steady power, so treat the time as a minimum.
What charger power should I enter?
Use the lower of the charger rating and the maximum your car accepts. A 22 kW charger cannot speed up a car that accepts only 7.4 kW on AC.
Does the efficiency figure matter?
Yes. Heat and conversion losses mean you pay for more energy than reaches the battery. A range of 85 to 92 percent is common.
These calculators give estimates based on the numbers you enter. Real results vary with vehicle, tariff, weather and driving habits.