How long does it take to charge an EV? kW, kWh and the 80% rule
A simple way to estimate charging time at any station, and why a 60 kW charger doesn't always charge at 60 kW.
"60 kW charger" sounds simple, but most drivers find their EV rarely charges at the full number on the sign. Here's how to estimate charging time yourself, in under a minute.
kW vs kWh, in one line each
- kWh (kilowatt-hour) is how much energy your battery holds. Think of it as the size of the fuel tank.
- kW (kilowatt) is how fast energy flows in. Think of it as how fast the pump fills the tank.
A 30 kWh battery is the tank. A 7.2 kW charger is the pump.
The basic formula
Charging time (hours) ≈ energy you want to add (kWh) ÷ charging power (kW)
Example: your car has a 30 kWh battery and you want to go from 20% to 80%. That's 60% of 30 kWh, which is 18 kWh.
| Charger | Real power | Time for 18 kWh |
|---|---|---|
| 15A home socket | ~2.5 kW | ~7 hours |
| AC wallbox | ~7 kW | ~2.5 hours |
| DC fast charger | ~30 kW average | ~35–40 minutes |
These are rough estimates. Real-world time is usually a bit longer because of energy lost as heat.
Why you rarely get the full kW
1. Your car sets the limit, not the charger
Every EV has a maximum power it will accept. If your car accepts up to 50 kW on DC, a 120 kW charger still charges at 50 kW or less. On AC, the onboard charger sets the limit, often between 3.3 kW and 11 kW.
2. Charging slows down after about 80%
Batteries charge fastest when they're fairly empty. Above roughly 80%, the car reduces the power to protect the battery. The last 20% can take almost as long as the 20% to 80% stretch.
That's why, on road trips, it's usually quickest to charge to about 80% and move on, rather than waiting for 100%.
3. Temperature matters
A very hot or very cold battery charges more slowly. In Indian summers, a battery that's hot after a long highway drive may charge slower for the first few minutes.
4. Shared chargers can split power
Some stations share power between two cars. If someone is plugged in next to you, you may both charge slower.
Quick rules of thumb
- Daily driving: charge on AC at home or work, and let it run overnight.
- Road trips: use DC fast chargers, arrive around 10–20%, leave around 80%.
- Pick the right charger: a charger much faster than your car accepts won't save time, but it may cost more per kWh.
You can compare charger speeds and prices per kWh across networks on our map.
Not sure which plug your EV uses? Read our guide to EV charging connectors in India.