How long does it take to charge an electric car at home

How to calculate EV charging time

Charging time is the energy drawn from the grid divided by the power the car actually charges at. The calculator works in four steps:

1. Energy into the battery: usable capacity × (target charge - starting charge). A 75 kWh battery from 20% to 80% takes 45 kWh.
2. Real power: the lower of the outlet or charger (EVSE) and the car's onboard charger. On AC the onboard charger converts the current for the battery, so it caps the rate; the Department of Energy lists the vehicle's internal charger capacity among the factors that set charging time.
3. Energy from the grid: some energy is lost in the cable, the onboard charger and the battery. The German automobile club ADAC measured losses of 12.7% to 24.2% on a 2.3 kW household socket and 5.1% to 7.0% on an 11 kW wallbox across five cars. The calculator uses 14% on Level 1 (or a household socket) and 7% on Level 2; you can change both in the advanced options.
4. Time: kWh from the grid ÷ kW. Enter your price per kWh and you also get the cost of the charge.

For the yearly figure it starts from your miles (or kilometres) and the consumption on your trip computer, then adds the same losses, since the trip computer counts the energy leaving the battery and not what was lost while charging. If your car shows mi/kWh, divide 100 by it: 3.3 mi/kWh is about 30 kWh/100 mi. If it shows Wh/mi, divide by 10: 300 Wh/mi is 30 kWh/100 mi.

A worked example

In the US. The calculator opens with a 75 kWh usable battery, an 11.5 kW onboard charger and a 48 amp Level 2 charger (240 V × 48 A = 11.52 kW).

• Energy into the battery: 75 × 0.6 = 45 kWh
• Power: 11.5 kW (charger and car match)
• From the grid, with 7% losses: 45 ÷ 0.93 = 48.4 kWh
• Time: 48.4 ÷ 11.5 = 4 h 12 min
• Per year, 12,000 miles at 30 kWh/100 mi: 3,600 kWh into the battery, 3,871 kWh from the grid

At an example price of $0.17 per kWh, that charge costs $8.23 and the year $658.06. Use the rate on your own bill.

In kilometres (UK and elsewhere). With a 60 kWh battery, an 11 kW onboard charger and an 11 kW wallbox, 20% to 80% takes 36 kWh in the battery, 38.7 kWh from the grid and 3 h 31 min. On a 7.4 kW single-phase wallbox it takes 5 h 14 min, if the car accepts 32 A on one phase. Not every three-phase car does: some charge at 16 A on a single-phase wallbox, which is 3.7 kW and 10 h 28 min. Check the AC charging line on your car's spec sheet.

EV charging time chart

From 20% to 80%, with an 11.5 kW onboard charger and the calculator's losses (14% on Level 1, 7% on Level 2):

Usable battery	Level 1, 12 A	Level 2, 32 A	Level 2, 48 A
60 kWh	29 h 4 min	5 h 2 min	3 h 22 min
75 kWh	36 h 20 min	6 h 18 min	4 h 12 min
100 kWh	48 h 27 min	8 h 24 min	5 h 37 min
130 kWh	62 h 59 min	10 h 55 min	7 h 18 min

Level 1 suits a car that drives little each day and sits plugged in overnight. For a full battery from low, Level 2 is the practical choice.

Which Level 2 charger to buy

Home charging equipment comes in a few sizes, and the power is volts × amps:

• Level 1: 120 V × 12 A = 1.44 kW, on a standard 15 amp outlet circuit
• Level 2, 32 A: 240 V × 32 A = 7.68 kW
• Level 2, 40 A: 240 V × 40 A = 9.6 kW
• Level 2, 48 A: 240 V × 48 A = 11.52 kW
• Level 2, 80 A: 240 V × 80 A = 19.2 kW, the top of Level 2

Buy the smallest charger that reaches your car's onboard charger, listed in the specs as the maximum AC charging rate in kW. A bigger one costs more and charges no faster. The calculator picks it for you and prints it on the receipt. In the UK and Europe the same rule applies to wallboxes: 3.7 and 7.4 kW single-phase, 11 and 22 kW three-phase. Germany is the exception: single-phase charging stops at 4.6 kW (20 A), so the 7.4 kW single-phase wallbox is not installed there.

Ask an electrician to check your panel and size the circuit before you buy: the Department of Energy notes that some homes do not have enough electrical capacity for Level 2.

Common mistakes

• Buying the biggest charger. Above the onboard charger's rating the time stays the same: in the drawing, every bar past that power has the same length.
• Using the gross battery size. What counts is the usable capacity, which is lower than the gross figure; check the spec sheet or the owner's manual.
• Forgetting charging losses. The kWh on your bill are more than the kWh that reached the battery, and the gap is bigger on Level 1.
• Expecting the same pace up to 100%. Charging power changes with the battery's state of charge and usually drops as it fills: above 80%, allow some extra time.
• A single-phase car on a three-phase wallbox (UK and Europe). A single-phase onboard charger draws from one phase only, so on a three-phase 16 A wallbox it charges at 3.7 kW, not 11 kW.