EV Charging Time Calculator

Multiply usable battery capacity by the percentage you want to add, then divide the resulting kWh by effective charging power. Effective power is the lowest of the station’s available output, the car’s AC or DC limit and its charging-curve limit at that battery level. Losses and DC taper make real charging slower than the basic calculation.

Source: US Alternative Fuels Data Center

A kilowatt, or kW, measures charging power: the rate at which energy can be transferred. A kilowatt-hour, or kWh, measures energy: the amount stored or delivered. A charger supplying 7 kW for one hour can theoretically deliver 7 kWh before losses.

Source: US Department of Energy

For a 60 kWh usable battery charging from 20% to 80%, theoretical times are about 5 hours 9 minutes at 7 kW, 3 hours 16 minutes at 11 kW and 1 hour 38 minutes at 22 kW. Real times are longer, and 22 kW gives no advantage if the vehicle accepts only 11 kW AC.

For the same 60 kWh battery charging from 20% to 80%, constant-power mathematical minimums are about 43 minutes at 50 kW, 14 minutes at 150 kW and 6 minutes at 350 kW. Actual DC charging takes longer because the car may not accept the station’s full rating and power changes during the session.

No. A 350 kW station only helps when the vehicle can accept more than 150 kW during a meaningful part of its charging curve. The vehicle limit, state of charge, battery temperature and shared station power can remove the expected advantage.

Source: UK charging infrastructure statistics guidance

Battery management systems commonly reduce DC charging power as the battery fills. Charging above about 80% can therefore take disproportionately longer. The exact taper point and curve vary by vehicle, temperature and battery condition.

Source: US EPA charging basics

The displayed rating is a maximum, not a guaranteed constant rate. The car’s maximum AC or DC rate, current battery level, battery temperature, battery-management system, charger load sharing and available site power can all reduce delivery.

Source: UK Department for Transport

Usually not. With AC charging, the car’s onboard charger converts AC electricity to DC, so its onboard AC rating limits speed. DC fast charging bypasses that onboard conversion equipment and is subject to a separate vehicle DC limit and charging curve.

Source: US Department of Energy EVSE training

Yes. Some energy is lost through the cable, power conversion, battery conditioning and heat. The charger must therefore deliver more energy than the amount ultimately stored in the battery. The calculator exposes its efficiency assumption so you can change it.

Source: US EPA fuel economy and range testing

It is an estimate. Accuracy improves when usable battery capacity, AC and DC limits and a vehicle-specific charging curve are known. Actual time can still change with battery level, age and temperature, vehicle configuration, charger condition and site demand.

Source: US Alternative Fuels Data Center