What Does kW Mean for EV Charging?
kW (kilowatt) is the rate of charging — how fast energy flows into your battery. kWh (kilowatt-hour) is the amount of energy stored. A 50 kW charger delivers 50 kWh in an hour if the car accepts it for the whole hour. Since a typical EV needs roughly 15–20 kWh per 100 km, a 50 kW charger adds around 250–330 km of range per hour in ideal conditions — and a 150 kW charger roughly three times that.
The one formula you need
Time (hours) ≈ energy you need (kWh) ÷ power you are getting (kW)
If your 60 kWh battery is at 20% and you want 80%, you need 60 × 0.6 = 36 kWh. At 50 kW that is about 43 minutes in theory. In practice add 10–25%, because charging slows as the battery fills.
What each power level means in practice
| Power | Type | Range added per hour* | 10–80% on a 60 kWh battery | Where you find it |
|---|---|---|---|---|
| 2.3 kW | AC, domestic socket | ~13 km | ~18 hours | Household plug (emergency use) |
| 7.4 kW | AC, single-phase | ~40 km | ~5 h 40 m | Home wallbox, on-street posts |
| 11 kW | AC, three-phase | ~60 km | ~3 h 50 m | Home and workplace |
| 22 kW | AC, three-phase | ~120 km | ~1 h 55 m | Car parks, destination charging |
| 50 kW | DC rapid | ~270 km | ~50 minutes | Older motorway and retail sites |
| 150 kW | DC ultra-rapid | ~800 km | ~25 minutes | Modern motorway hubs |
| 350 kW | DC ultra-rapid | ~1,900 km | ~18 minutes** | Flagship charging hubs |
* Assuming roughly 18 kWh per 100 km and that the car sustains the rate. ** Only cars with 800 V architecture get close to this; most cars cap well below 350 kW.
Why you rarely see the headline number
Three things limit the power you actually receive:
- Your car's maximum accepted rate. Many popular EVs peak at 100–150 kW on DC. Plugging into a 350 kW charger will not exceed that.
- State of charge. The charging curve tapers as the battery fills — steeply above 80%.
- Battery temperature. A cold battery accepts much less power. Some cars precondition the pack when you navigate to a fast charger; if yours does, use it.
A fourth, more mundane one: some sites split a cabinet's output between two bays, so a "150 kW" charger may deliver 75 kW when both bays are in use.
Does a bigger number mean a better stop?
Only up to your car's limit. If your EV peaks at 120 kW, a 150 kW charger and a 350 kW charger will give you almost identical stop times — so pick the one that is closer, cheaper or more likely to be free. This is exactly the kind of decision a filtered map makes easy: set the minimum power you need and ignore the rest.
kW on your electricity bill
You pay per kWh, not per kW. A 22 kW post and a 7.4 kW post delivering the same 20 kWh cost the same in energy terms — the faster one just gets you there sooner. What does change price is the tariff: DC fast charging typically costs 1.5–3× more per kWh than home AC charging.