EV Charging Time Calculator

How the calculation works

The maths is simple at heart. First we work out the energy you actually need to put in:

Energy needed (kWh) = battery size x (target % minus start %) / 100

Then we divide that energy by the charger power to get the time. We also factor in a small efficiency loss, because some energy is lost as heat in the cables, charger and battery rather than being stored:

Charging time = energy needed / (charger power x efficiency)

For a home or workplace AC charger (3kW, 7kW or 22kW) the speed stays fairly steady, so this works cleanly.

Why rapid charging slows down near full

Rapid DC chargers (50kW and 150kW) behave differently. They charge fast up to around 80%, then deliberately slow right down to protect the battery. That is why you rarely see a car pull full rapid power all the way to 100%.

To keep the estimate honest, this calculator models the rapid taper: any charge below 80% is calculated at the full rated speed, and the portion above 80% is calculated at roughly half the rated speed. It is a simplification, but it gets you far closer to reality than a flat calculation would.

For this reason, charging from 20% to 80% on a rapid charger is the sweet spot for a quick top-up, and that is the default we have pre-filled.

Why real-world charging is slower

Treat the result as a best-case estimate. In the real world your charge can take longer because of:

Cold weather slowing the chemistry and triggering battery pre-heating
A nearly full or nearly empty battery where the car limits the current
Shared chargers that split their power between two cars
Your car capping the charge rate below the charger maximum (a 7kW car will not pull 22kW)

If your charge consistently takes far longer than the estimate, the limiting factor is usually your car, not the charger.

Assumptions and accuracy

Estimates assume a steady charge with a 90% efficiency loss, a rapid taper above 80%, and around 3.5 miles per kWh for the miles-added figure. Real charging is slower in the cold and when the battery is very full or very empty.

These figures are estimates, not a guarantee. Last updated 2026-06-11.

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FAQs

How long does it take to charge an electric car?

It depends on the battery size and charger. A typical 60kWh EV from 20% to 80% takes roughly 8 hours on a 7kW home charger, under 3 hours on a 22kW charger, and around 35 to 45 minutes on a 50kW rapid charger. Use the calculator above for your exact figures.

How long does a 3-pin plug take to charge an EV?

A standard 3-pin domestic socket charges at around 2.3kW to 3kW. For a 60kWh battery that is a slow trickle: a full charge can take well over 24 hours, which is why a 3-pin plug is best kept for emergencies or topping up overnight.

Why does rapid charging slow down at 80%?

The car deliberately reduces the charge rate above 80% to protect the battery cells and avoid overheating. This is normal and built into every EV. It is why most rapid charging guidance suggests charging to 80% and driving on rather than waiting for the last 20%.

Does charging efficiency really matter?

Yes, a little. Around 8% to 15% of the energy is lost as heat during charging, so the battery takes slightly longer to fill than the raw maths suggests. We default to 90% efficiency, which is sensible for a home AC charger.

Will charging to 100% damage my battery?

Charging to 100% occasionally is fine, and useful before a long trip. For daily use, most manufacturers suggest keeping the battery between 20% and 80% to slow long-term wear. Your handbook will give the specific advice for your model.