Kilowatt

A kilowatt (kW) is a unit of power equal to 1,000 watts. It measures how fast energy flows, so a charger's kW rating sets how quickly it can fill a battery.

For AC chargers, kW equals volts times amps divided by 1,000. A 32 amp charger at 240 volts gives 7.68 kW, and a 12 amp, 120 volt outlet gives 1.44 kW. Divide the kilowatt-hours you need by the kW to get hours.

The Department of Energy lists Level 2 chargers from 2.9 kW to 19.2 kW and DC fast chargers up to 500 kW. The guide to home EV charger sizes shows the kW for each common charger, and the EV charging time calculator takes amps and volts or kW.