"How long does it take to charge?" is one of the most common questions about electric cars, and the honest answer is "it depends". It depends on the charger, the car, how full the battery already is and even the weather. Fortunately, a simple calculation gets you close, and knowing the limiting factors explains the rest.
This guide gives the formula, practical tables for typical batteries and chargers, and the reasons real sessions differ from the theory.
- Charging time ≈ energy needed (kWh) ÷ effective charging power (kW).
- On AC, the car's on-board charger often limits power to 7.4 or 11 kW, whatever the wallbox rating.
- On DC, a typical 10–80% charge takes about 20–40 minutes on a 150 kW charger, depending on the car.
- Charging slows above roughly 80% state of charge, so stopping at 80% saves a lot of time on fast chargers.
The basic formula
Charging time (hours) ≈ Energy needed (kWh) ÷ Effective charging power (kW)
Energy needed is the battery capacity multiplied by the share you want to add, plus about 5–10% for charging losses on AC. Effective power is the lowest of three limits: the charger's power, the car's maximum for that type of charging, and any limit set by the site's load management. If the units are unclear, our article on kW vs kWh explains them.
AC charging times
For AC charging, the conversion to DC happens in the car's on-board charger, which typically handles 7.4 kW (single-phase) or 11 kW (three-phase), and on some models 22 kW.
| Energy to add | 3.7 kW | 7.4 kW | 11 kW | 22 kW* |
|---|---|---|---|---|
| 20 kWh (about 120 km) | ~6 h | ~3 h | ~2 h | ~1 h |
| 40 kWh | ~12 h | ~6 h | ~4 h | ~2 h |
| 60 kWh | ~18 h | ~9 h | ~6 h | ~3 h |
*Only for cars with a 22 kW on-board charger; others charge at their own maximum, usually 11 kW.
Whether a car can use three-phase power, and how this differs between countries, is covered in our guide to single-phase vs three-phase charging. Our comparison of 11 kW and 22 kW wallboxes helps decide which to install.
DC fast-charging times
With DC, power depends on the car's battery and how the manufacturer manages the charging curve. The table shows typical times for a 10–80% charge.
| Battery (usable) | 50 kW charger | 150 kW charger | 300 kW charger |
|---|---|---|---|
| 40 kWh | ~35–45 min | ~25–35 min (car-limited) | ~25–35 min (car-limited) |
| 60 kWh | ~50–60 min | ~25–35 min | ~20–30 min |
| 80 kWh | ~65–80 min | ~30–40 min | ~20–30 min |
These are typical ranges. Some cars with 800-volt architecture charge much faster on high-power chargers; others peak well below 150 kW. A more powerful charger only helps if the car can accept the power.
Why real charging times vary
- State of charge: power drops as the battery fills, especially above 80%. Our article on the charging curve explains why.
- Temperature: cold batteries accept less power. Preconditioning the battery while driving to a fast charger helps.
- On-board charger: on AC, it is usually the real limit, not the wallbox.
- Power sharing: some DC chargers split power between two cars, and load management can reduce AC power at busy sites.
- Cable and connection: long cables, worn connectors or a single-phase supply reduce effective power.
What this means for site planning
For operators, charging time links directly to how many cars a charger can serve. A site where cars stay two hours needs very different hardware from a motorway stop where drivers want to leave within 25 minutes. Match the charger to the dwell time and the energy drivers typically need, rather than installing the highest power possible. Our guide to choosing a charging site covers this in more detail.
Monitoring real charging speeds
A charging management system receives power and energy readings from each charger through OCPP MeterValues. Looking at average power per session by charger type shows whether chargers deliver what drivers expect, or whether limits, faults or power sharing slow things down.
Frequently asked questions
How long does it take to charge an electric car at home?
With a 7.4 or 11 kW wallbox, most cars recover a typical day's driving in one to three hours and a full charge overnight. A household socket at around 2–3 kW can take 15 hours or more for a large battery.
Why does fast charging slow down after 80%?
The battery management system reduces power as cells fill, to protect battery life and avoid overheating. The last 20% often takes as long as the 10–80% section.
Does a 22 kW charger always charge twice as fast as 11 kW?
No. Only cars with a 22 kW on-board charger benefit. Most cars charge at 11 kW on a 22 kW point.
Is it bad to always use fast chargers?
Modern batteries are designed for regular fast charging, but frequent high-power charging at extreme temperatures can contribute to faster wear. Manufacturers' guidance varies by model.
Track real charging power, energy and session duration per charger and connector in one dashboard. Explore Üreticy OCPP software or contact us.