Compare electric cars rated in different units. Convert kWh/100 mi, kWh/100 km, Wh/mi, Wh/km, mi/kWh, km/kWh, MPGe and Le/100 km in one step, then see the range on your battery and the energy cost per 100 miles.
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Efficiency
Type the figure from a window sticker, trip computer or review
Optional: range and cost
kWh
Leave empty to skip the range estimate
$/kWh
Your rate per kWh; leave empty to skip
Enter your values to see the result.
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How to use the EV Efficiency Converter
Type the efficiency figure you have, for example 30 or 4.1.
Pick the From unit it is quoted in and the To unit you want.
Add your battery size and electricity price (optional) for range and cost.
Press Convert to see the result in every unit with the steps.
Compare with the equivalents table and the vehicle-class chart.
EV efficiency conversion formulas
All conversions run through one base value, watt-hours per mile. One mile is exactly 1.609344 km, and the EPA sets 33.705 kWh as the energy in one US gallon of gasoline (8.904 kWh per litre; Natural Resources Canada rounds it to 8.9).
From → To
Formula
Example
kWh/100 mi → kWh/100 km
÷ 1.609344
30 → 18.64
kWh/100 km → kWh/100 mi
× 1.609344
16 → 25.75
kWh/100 mi → mi/kWh
100 ÷ value
30 → 3.33
kWh/100 km → km/kWh
100 ÷ value
16 → 6.25
mi/kWh → kWh/100 km
62.137 ÷ value
4 → 15.53
Wh/mi → kWh/100 mi
÷ 10
280 → 28
Wh/km → mi/kWh
621.37 ÷ value
160 → 3.88
kWh/100 mi → MPGe
3,370.5 ÷ value
30 → 112
MPGe → mi/kWh
value ÷ 33.705
120 → 3.56
kWh/100 km → Le/100 km
÷ 8.904
18 → 2.02
What the numbers mean on the road
Efficiency is the single best predictor of range and running cost. With a 75 kWh usable battery, 25 kWh/100 mi gives about 300 miles, while 40 kWh/100 mi gives about 188 miles. Energy cost follows the same line: at $0.17 per kWh, each 10 kWh/100 mi adds $1.70 to every 100 miles.
Vehicle type (typical)
kWh/100 mi
Wh/km
mi/kWh
MPGe
Small hatchback or efficient sedan
24–28
150–175
3.6–4.2
120–140
Compact crossover
28–33
175–205
3.0–3.6
100–120
Mid-size or 3-row SUV
33–40
205–250
2.5–3.0
84–100
Full-size pickup or large SUV
42–52
260–325
1.9–2.4
65–80
Ranges are rounded examples of combined ratings, not figures for a specific model. Real-world use varies with speed, temperature, wheels and climate control.
Window sticker vs trip computer: sticker values include charging losses; dashboard values usually do not, so they read lower.
Winter: cabin and battery heating can raise consumption by 20–40% on short trips.
Highway speed: going from 65 to 75 mph often costs 10–15% more energy because drag rises with the square of speed.
Frequently asked questions
How do I convert kWh/100 km to mi/kWh?
Use mi/kWh = 100 ÷ (kWh/100 km × 1.609344). For example, 16 kWh/100 km equals 25.75 kWh/100 mi, and 100 ÷ 25.75 = 3.88 mi/kWh. Going the other way, kWh/100 km = 62.137 ÷ mi/kWh.
How is MPGe calculated for an electric car?
The US EPA treats 33.705 kWh of electricity as equal to the energy in one gallon of gasoline. MPGe = 33.705 ÷ (kWh used per mile), so a car using 30 kWh/100 mi (0.30 kWh per mile) is rated 33.705 ÷ 0.30 = 112 MPGe.
What is a good EV efficiency?
Most electric cars use roughly 25–35 kWh/100 mi (about 155–220 Wh/km, or 2.9–4 mi/kWh). Small efficient cars can beat 25 kWh/100 mi, while large SUVs and pickups often use 40–50 kWh/100 mi. Cold weather, high speed and towing raise consumption.
What is the difference between Wh/mi and kWh/100 mi?
They are the same quantity scaled by 10: 1 kWh/100 mi = 10 Wh/mi. 300 Wh/mi is 30 kWh/100 mi. Trip computers often show Wh/mi or Wh/km, while window stickers use kWh/100 mi.
Why do some units go up and others go down when a car is more efficient?
kWh/100 mi, Wh/km and Le/100 km measure energy used per distance, so lower is better. mi/kWh, km/kWh and MPGe measure distance per unit of energy, so higher is better. Each pair is a reciprocal, which is why you cannot just multiply by a fixed number between them.
Do EPA and WLTP ratings convert directly?
The units convert exactly, but the test cycles differ. WLTP (Europe) figures are usually more optimistic than EPA figures for the same car, so a converted WLTP number will often look better than the car's EPA rating.
Does the figure include charging losses?
EPA kWh/100 mi and MPGe are measured from the wall, so they include charging losses. Trip-computer Wh/mi readings usually measure energy taken from the battery and come out roughly 10–15% lower than wall-to-wheels figures.
Are all the tools on FreeToolCabin tested for quality and accuracy?
Yes! Every tool on our site undergoes automated Q/A testing in real browser environments to ensure high precision, correct output, and zero errors. If you happen to spot a bug or have a suggestion, please contact us at [email protected] and our team will review it right away.