EV Charging Speed Calculator
Calculate how fast different charger types add range to your EV. Compare charging speed and estimated charge time across all charger types at a glance — from portable chargers to ultra rapid DC.
EV charging speed
Typical EV charging speed in New Zealand
The table below shows estimated range added per hour for each charger type, with visual bars for easy comparison.
| Charger type | Power | Range added per hour |
|---|---|---|
| Portable charger | 2.3 kW | |
| AC wall charger | 7 kW | |
| 3-phase AC charger | 22 kW | |
| DC fast charger | 50 kW | |
| DC rapid charger | 150 kW | |
| Ultra rapid charger | 250 kW |
Based on a typical EV (16 kWh per 100 km). Real-world speeds depend on battery temperature, state of charge and charger availability. Your own car caps this: once its maximum charge rate is reached, a more powerful charger adds nothing.
How this calculator works
This calculator estimates how much range a charger adds to your EV per hour based on the charger power and your vehicle's efficiency. Each card also shows the estimated time to charge from 10% to 80%, giving you a practical sense of how long each charger type takes.
If your vehicle has a maximum DC charging speed, chargers above that limit will show the effective speed your vehicle can actually achieve, with a warning indicating the vehicle limit.
Formulas
Charging speed (km/hr) = Charging power (kW) ÷ EV efficiency (kWh per 100 km) × 100
10–80% charge time = Battery size × 0.7 ÷ Charging power
Worked example
Charging power: 7 kW (AC wall charger)
EV efficiency: 16 kWh per 100 km
Battery size: 75 kWh
Charging speed: 7 ÷ 16 × 100 = ~44 km per hour
10–80% charge time: 75 × 0.7 ÷ 7 = 7 hr 30 min
Real-world note
This calculator assumes a constant charging rate. In practice, DC fast charging speed varies across the charging session — it is fastest at lower battery levels and slows as the battery fills. The range-per-hour figures shown are ideal maximums for each charger type. Actual speeds depend on the vehicle's charging curve, battery temperature and charger availability.
Frequently asked questions
How fast does a home charger add range?
A standard 7 kW AC wall charger adds around 44 km of range per hour for a typical EV with 16 kWh per 100 km efficiency. A portable 2.3 kW charger adds around 14 km per hour. Most EV owners with a wall charger plug in overnight and start each day with a full battery, so the slower speed is rarely an issue in practice.
Why is my car slower than the charger's advertised power?
Because the charger's rating is a ceiling, not a promise. Every EV has its own maximum DC charge rate, and if that limit is below the charger's output, the extra capacity does nothing for you. Plugging a car that peaks at 88 kW into a 350 kW charger gets you 88 kW. This is why the comparison above uses your own vehicle's limit once you have set it: quoting speeds your car cannot physically accept would be misleading.
Is it worth paying more for an ultra-rapid charger?
Only if your car can use the extra power. If your vehicle tops out around 50 to 90 kW, an ultra-rapid unit will charge it no faster than a standard DC fast charger, and you may pay a higher rate per kilowatt-hour for nothing. If your car accepts 150 kW or more, the time saving on a long drive is real and usually worth it. Check your vehicle's maximum DC rate before deciding, which is the figure the calculator above uses.
Why does charging speed drop as the battery fills?
To protect the battery. As cells approach full, the car progressively reduces the current it accepts, a behaviour known as the charging curve. The taper usually becomes pronounced somewhere above 80 percent, which is why the last 20 percent can take as long as the first 60. On a long drive it is normally faster overall to make two shorter stops to 80 percent than one long stop to 100 percent.
Does a bigger battery charge faster?
It adds range faster at the same power, which is not quite the same thing. A larger battery generally accepts higher power for longer before tapering, and each kilowatt-hour delivered buys fewer kilometres in a heavy long-range car than in a light efficient one. The figure worth comparing between vehicles is kilometres of range added per hour, which is what this calculator shows, rather than kilowatts alone.
Why is home charging so much slower than public charging?
Home charging is alternating current, limited by your household supply and by the car's onboard charger, typically somewhere between 2 kW from a standard power point and 7 to 22 kW from a dedicated wall unit. Public fast chargers supply direct current straight to the battery, bypassing that onboard limit entirely. The practical difference matters less than it sounds: a car parked overnight for ten hours has far more time available than a car stopped for twenty minutes, so a slow charger with time on its side still fills the battery.
