Electric Vehicle Efficiency Converter
Convert EV energy consumption between Wh/km, Wh/mile, miles per kWh, km per kWh, and MPGe.
Type in any field and the others update automatically.
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Electric vehicle efficiency measures how much energy a car uses per unit of distance. Unlike gasoline cars (which use L/100km or mpg), EVs use energy metrics.
The core unit is Wh/km (watt-hours per kilometer):
- A smaller number means a more efficient vehicle (uses less energy per km)
- A larger number means more energy per km (heavier, less aerodynamic, or more powerful car)
Key conversion relationships:
- Wh/km → Wh/mile: Wh/mile = Wh/km × 1.60934
- Wh/km → km/kWh: km/kWh = 1000 ÷ Wh/km (they are reciprocals)
- Wh/km → miles/kWh: miles/kWh = 1000 ÷ (Wh/km × 1.60934)
- Wh/km → MPGe: MPGe = 33,705 ÷ (Wh/mile), which is the US EPA formula
MPGe (Miles per Gallon equivalent): The US EPA defined 33.7 kWh as the energy equivalent of one gallon of gasoline. MPGe = 33,705 Wh ÷ Wh/mile
Typical EV efficiency ranges:
Every conversion in this table comes straight out of the three formulas above, so you can check any row against the calculator.
| Vehicle class | Wh/km | Wh/mile | miles/kWh | MPGe |
|---|---|---|---|---|
| Small efficient EV | 120 | 193 | 5.18 | 175 |
| Tesla Model 3 class | 140 – 165 | 225 – 266 | 3.77 – 4.44 | 127 – 150 |
| Mid-size EV (Rivian R1T class) | 250 – 300 | 402 – 483 | 2.07 – 2.49 | 70 – 84 |
| Large EV truck or SUV | 300 – 400 | 483 – 644 | 1.55 – 2.07 | 52 – 70 |
Read the last two columns backwards from the first: fewer watt-hours per kilometre means more miles per kilowatt-hour and a higher MPGe. It is easy to get that inversion wrong when writing figures out by hand, and a table where a thriftier car scores a lower MPGe is a table with a mistake in it.
- Cold weather impact: EVs typically use 15–40% more energy in temperatures below 0°C (32°F)
- Highway vs city: Unlike gas cars, EVs are often more efficient in city driving due to regenerative braking
Comparing EV and gasoline cost per km:
- Average gas car (8 L/100km at $1.60/L) = $0.128 per km
- Average EV (160 Wh/km at $0.15/kWh) = $0.024 per km
- EVs are typically 4–6x cheaper to fuel per km in most countries
How we build and check this converter
This converter runs entirely in your browser, so the numbers you enter stay on your device. The math behind it is written by hand and tested against worked examples and standard references before the page goes live.
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