Miles of range per hour
Miles of range per hour expresses charging speed in practical terms: how much driving distance the battery gains each hour. It equals charging power (kW) × vehicle efficiency (miles per kWh) — typically 25–45 miles per hour on a home Level 2 charger.
An efficient sedan (4 mi/kWh) on an 11.5 kW charger gains ~46 miles per hour; a heavy truck (2 mi/kWh) on the same charger gains ~23.
This site computes the figure per charger-vehicle pair from EPA range and battery capacity, which is more honest than quoting a single number for a charger.
| Formula | miles per hour = charging power (kW) × vehicle efficiency (mi/kWh) |
|---|---|
| Typical efficiency | Efficient sedan 3.5–4.2 mi/kWh · crossover 2.8–3.4 · full-size electric truck 1.8–2.4 |
| 11.5 kW (48 A) | About 40 mi/h on a 3.5 mi/kWh car; about 23 mi/h on a 2 mi/kWh truck |
| 9.6 kW (40 A) | About 34 mi/h on the same 3.5 mi/kWh car |
| 7.7 kW (32 A) | About 27 mi/h on the same 3.5 mi/kWh car |
| 1.44 kW (Level 1) | 3–5 mi/h |
| Real-world correction | Subtract 8–15% for AC-to-battery losses; more in cold weather |
Why the number moves so much
Two variables set it, and a charger manufacturer controls only one. When a spec sheet claims “up to 44 miles per hour”, it is quoting 11.5 kW multiplied by roughly 3.8 mi/kWh — an efficient sedan in mild weather. Put the same charger on a Ford F-150 Lightning at about 2 mi/kWh and the honest figure is 23 miles per hour. Neither number is a lie; the claim is just meaningless without naming a car.
Vehicle efficiency is not a constant either. EPA combined ratings are a mild-weather, mixed-cycle average. Winter driving at −7 °C with cabin heat, a cold pack and winter tyres commonly cuts real consumption by 25–40%, and sustained highway speed cuts it further. A car that manages 3.5 mi/kWh in September may manage 2.3 in January, which turns 40 miles per hour of charging into 26 — at exactly the time of year you are least inclined to wait.
The useful form of the number is therefore always a pair: a specific charger power and a specific vehicle. That is why every charger-vehicle combination on this site computes its own figure from EPA range and battery capacity rather than quoting one headline number per charger.
The losses between the meter and the odometer
AC Level 2 charging runs at roughly 85–92% wall-to-battery efficiency. The onboard charger’s AC-to-DC conversion is 92–94% of that; the rest goes to coolant pumps, contactors, the 12 V system, and battery thermal management. A charger delivering 11.5 kW at the wall is therefore putting somewhere around 10–10.6 kW into the cells, and your miles-per-hour figure should be computed from the smaller number.
At Level 1 the picture is worse, because the fixed overhead is the same few hundred watts but the input is only 1.4 kW. Efficiency there commonly falls to 75–85%, so the effective rate can drop below 3 miles per hour. In deep cold it can go to zero: a battery-heating or preconditioning cycle can consume the entire 1.4 kW input, leaving the pack no better off after a full night on the plug.
If you are reconciling costs, use the meter reading rather than the car’s display. The car reports energy into the battery; the utility bills you for energy through the wall; the gap between them is the 8–15% you never see on the dashboard. Over a 3,400 kWh year that is 270–510 kWh, or $45–$85 at $0.17/kWh.
How to use the number when buying
Do not size a charger from full-battery times, because nobody charges from empty at home. Size it from a normal day. Forty miles a day at 3.5 mi/kWh is 11.4 kWh: a 40 A charger delivers that in about 75 minutes, a 32 A charger in about 90, and Level 1 in eight hours. Framed that way, the difference between 40 A and 48 A is fifteen minutes on a night when you are asleep for eight.
Full-battery arithmetic only matters when you regularly arrive close to empty with a firm departure time, or when a time-of-use window is short. A 135 kWh Rivian R1S from empty is about 14 hours at 9.6 kW and 11.7 at 11.5 kW — that gap is the difference between finishing before a 6 a.m. departure and not. A 75 kWh Model 3 is 7.8 hours versus 6.5, which almost never matters.
The other place this number earns its keep is deciding whether Level 2 is needed at all. If your daily driving is under 30 miles in an efficient car, Level 1 at 4–5 miles per hour over a 12-hour overnight window covers it with room to spare, and the money is better spent elsewhere. Above that, or in anything heavy, the arithmetic stops working and a 240 V circuit is the answer.
Frequently asked questions
How many miles per hour does a Level 2 charger add?
Typically 20–45 miles of range per hour at home. Multiply the delivered power by the car’s efficiency: 11.5 kW on a 3.5 mi/kWh sedan is about 40 miles an hour, 9.6 kW on the same car about 34, and 11.5 kW on a 2 mi/kWh electric truck about 23. Subtract 8–15% for charging losses to get the real figure.
How do I calculate miles of range per hour?
Multiply charging power in kW by your car’s efficiency in miles per kWh. Find your efficiency by dividing EPA range by usable battery capacity — a 75 kWh Tesla Model 3 rated around 272 miles is about 3.6 mi/kWh. So on an 11.5 kW charger: 11.5 × 3.6 ≈ 41 miles per hour, or about 37 after losses.
Why is my car charging slower than the charger’s rating?
Most often your car’s onboard AC limit is lower than the charger’s output — that caps everything. Other causes: a 208 V supply instead of 240 V, voltage sag on a long run, the charger set below its maximum by a DIP switch, cold-weather battery conditioning consuming part of the input, or the car tapering as it approaches 100% state of charge.
How many miles per hour does Level 1 charging add?
Three to five for most EVs — 1.44 kW multiplied by 3–4 mi/kWh, less the larger charging losses that Level 1 incurs. A full-size electric truck gets under three. Over a 12-hour overnight window that is roughly 35–55 miles, which covers an average driving day for an efficient car and falls short for anything heavy.