MultiConvers

EV Charging Time Calculator

Estimate ideal plug-in time as energy to add divided by charger kilowatts, assuming that power stays constant. A 60 kWh pack from 20% to 80% is 36 kWh; at 7.2 kW that is 5 hours. Real DC sessions taper and usually take longer.

Updated

How to use

  1. Enter battery capacity in kWh and the start and target percentages (target at or above start).
  2. Enter charger power in kW — the lower of the station’s rating and the car’s onboard limit.
  3. Read ideal hours. Already-at-target (40% → 40%) is 0 hours.
  4. Use EV Charging Cost for money. This page does not apply efficiency losses or a taper curve.

How it works

Energy to add is the same first line as the cost tool: capacity × (target − start) / 100. Time is that energy divided by charger kW. There is no efficiency term here, so 36 kWh at 7.2 kW is exactly 5 hours. Losses on AC make the wall clock a little longer; the page will not stretch the result for you.

Constant power is the fiction. DC fast chargers advertise a peak, then cut current as state of charge climbs — often sharply after 80%. Cold cells accept less. A 150 kW stall cannot push 150 kW into a car whose inlet is limited to 50 kW; type the bottleneck, not the poster.

Home AC at 7.2 kW or 11 kW is closer to the ideal line, still short of it when the car preconditions the cabin or the pack is already warm. Preconditioning draws power that never becomes miles. This calculator does not model that load.

Same start and target is zero time, not an error. Target below start is rejected. There is no overnight “crosses midnight” flag because the result is a duration in hours, not a pair of clock faces. For clock subtraction, use Time Duration.

Horsepower-to-kW is a unit conversion if a brochure quotes hp and you need kW for this field. Cost, idle fees and parking live on other pages.

Formula

Energy (kWh) = capacity × (target % − start %) ÷ 100
Hours = energy ÷ charger kW

Worked examples

  • 20–80% on a 60 kWh pack at 7.2 kW

    60 kWh, 20% → 80%, 7.2 kW → 36 kWh, 5 hours

  • Already at target

    50 kWh, 40% → 40%, 11 kW → 0 hours

Useful notes

  • Assumes constant charger power. DC fast charging tapers near the top of the pack.
  • This is time, not cost. Use EV Charging Cost for the bill.
  • Use the lower of station kW and the car’s charge limit — the page does not pick it.

FAQ

Why is my real charge slower than this?

Power is not constant. Fast chargers taper, cold batteries accept less current, and some of the meter’s energy is lost as heat.

Should I use the car’s peak kW or the station’s?

Use the lower of the two. A 150 kW stall cannot push 150 kW into a car whose onboard limit is 50 kW.

Does this include charging losses?

No. It divides battery energy by charger kW. Losses make grid energy higher and can stretch clock time slightly on AC.

Why is 20–80% often recommended if this is linear?

The algebra is linear; real DC power is not. Taper above ~80% is why many drivers stop there. This page will still compute 80–100% as if power held.

Can I enter 0 kW?

No. Time would be undefined. The charger power must be a positive kilowatt figure.

Related tools

See all Energy tools.

Sources