Use this EV charging speed calculator to find the driving range added per hour and per minute of charging, plus total range added over any charging duration.
EV Charging Speed Formula
EV charging speed is usually expressed as driving range added per hour of charging. It combines how fast the charger delivers energy with how far your car travels on that energy. First find the power that actually reaches the battery, then multiply by the vehicle’s distance per kilowatt-hour:
Pb = min(P, Pcap) * e Range per hour = Pb * d Range per minute = Range per hour / 60
Variables:
- P is the charger power in kilowatts (kW)
- Pcap is the vehicle’s maximum charging power in kW; if left blank there is no cap
- e is the charging efficiency as a decimal, so 90 percent is 0.90
- Pb is the effective power delivered to the battery in kW
- d is the vehicle efficiency expressed as distance per kWh (mi/kWh or km/kWh)
- Range per hour is the driving range added for each hour of charging
If your efficiency is shown in another unit, convert it to distance per kWh first: from kWh per 100 miles, d = 100 / value; from watt-hours per mile, d = 1000 / value; the kilometer units convert the same way. The distance unit of the answer follows the unit you entered, so a mile-based efficiency returns miles per hour and a kilometer-based efficiency returns kilometers per hour.
Note that this is charging speed, not charge time. Charging speed tells you how much range you gain per hour; it does not tell you how many hours are needed to reach a target state of charge, which depends on your battery size and starting level.
Range Added Per Hour by Charger
This table shows the range added per hour and per 30 minutes for common chargers, assuming a vehicle efficiency of 3.5 mi/kWh and 90 percent charging efficiency. Use it as a quick reference before you run your own numbers.
| Charger | Charger power | Power to battery | Miles per hour | Miles per 30 min |
|---|---|---|---|---|
| Level 1 (120V) | 1.4 kW | 1.26 kW | 4.4 | 2.2 |
| Level 2 (240V, 32A) | 7.7 kW | 6.93 kW | 24 | 12 |
| Level 2 (240V, 48A) | 11.5 kW | 10.35 kW | 36 | 18 |
| DC Fast | 50 kW | 45 kW | 158 | 79 |
| DC Fast | 150 kW | 135 kW | 473 | 236 |
The DC fast figures are peak values. In practice the car pulls that power only over part of the charge, so the average range per hour on a real fast-charging session is lower than the table suggests.
Example Problems
Example 1: Overnight Level 2 charging at home.
You plug into an 11.5 kW Level 2 charger. Your car does 3.5 mi/kWh and the charging efficiency is 90 percent. The power reaching the battery is 11.5 * 0.90 = 10.35 kW, so the range added per hour is 10.35 * 3.5 = 36.2 miles per hour, about 0.6 miles per minute. Over an 8 hour overnight session you add roughly 290 miles of range and about 82.8 kWh of energy to the battery.
Example 2: A DC fast-charging stop.
You pull into a 150 kW DC fast charger with the same 3.5 mi/kWh car and 90 percent efficiency. The battery receives 150 * 0.90 = 135 kW, so at peak the charger adds 135 * 3.5 = 472.5 miles per hour, close to 7.9 miles per minute. A 20 minute stop would add about 158 miles at that peak rate, though real-world tapering above roughly 80 percent state of charge means you usually see somewhat less.
Frequently Asked Questions
How many miles per hour does a Level 2 charger add?
A typical home Level 2 charger delivers 7 to 11.5 kW. For an average EV that does about 3.5 to 4 miles per kWh, that works out to roughly 20 to 40 miles of range per hour after charging losses. A 32 amp unit at 7.7 kW adds around 24 miles per hour, while a 48 amp unit at 11.5 kW adds around 36 miles per hour.
Why is DC fast charging so much faster?
DC fast chargers supply 50 kW to 350 kW directly to the battery, bypassing the car’s onboard AC charger, which is usually limited to about 7 to 11 kW. Because charging speed is proportional to power delivered, ten to thirty times more power means ten to thirty times more range added per minute, which is why a fast charger can add a couple hundred miles in the time a home charger adds twenty.
Does charging speed stay constant?
Not on DC fast charging. The battery accepts its highest power when it is fairly empty and the charger tapers the power as the battery fills, especially past about 80 percent, to protect the cells. AC Level 1 and Level 2 charging is closer to constant because the onboard charger is already the limiting factor, so the per-hour rate holds steady across most of the session.
