EV Efficiency Converter
One EV efficiency figure, every unit at once. Type a value in Wh/km, kWh/100km, km/kWh, Wh/mi, mi/kWh or kWh/100mi and instantly see it in all the others — plus what it means for your range when you add a battery capacity.
Enter a value to see conversions in all other units.
Share this conversion — the link prefills your values.
The six EV efficiency units, explained
EV efficiency is quoted two ways around. Consumption units say how much energy a distance costs — Wh/km, kWh/100km, Wh/mi and kWh/100mi, where lower is better.Efficiency units say how far a unit of energy takes you — km/kWh and mi/kWh, where higher is better. Because the two families are reciprocals, converting between them inverts the number: 160 Wh/km is the same as 16 kWh/100km, 6.25 km/kWh and about 3.9 mi/kWh.
| Unit | Family | Common in | Better when |
|---|---|---|---|
| Wh/km | Consumption | Tesla, metric dashboards | Lower |
| kWh/100km | Consumption | Europe, official figures | Lower |
| km/kWh | Efficiency | Metric reviews | Higher |
| Wh/mi | Consumption | Tesla (US/UK) | Lower |
| mi/kWh | Efficiency | North America, UK | Higher |
| kWh/100mi | Consumption | US EPA ratings | Lower |
Handy conversion rules of thumb
- Wh/km → kWh/100km:multiply by 10 — 155 Wh/km is 15.5 kWh/100km.
- Wh/km → km/kWh:divide 1000 by it — 200 Wh/km is 5 km/kWh.
- Wh/km → mi/kWh:divide 621.4 by it — 160 Wh/km is about 3.9 mi/kWh.
- mi/kWh → Wh/mi:divide 1000 by it — 4 mi/kWh is 250 Wh/mi.
Want the full background on what these units mean and what a good figure looks like? Read what is EV efficiency? — then measure your own with the efficiency calculator.
Frequently asked questions
What is the difference between Wh/km and kWh/100km?
They measure the same thing on different scales: multiply Wh/km by 10 to get kWh/100km. A car using 160 Wh/km is using 16 kWh/100km. Wh/km is convenient per kilometre, kWh/100km reads better over longer distances.
How do I convert Wh/km to mi/kWh?
Divide 621.37 by your Wh/km figure. For example, 160 Wh/km works out to about 3.9 mi/kWh. Because one is a consumption and the other an efficiency, the conversion inverts the number — which is exactly what this converter does for you.
Which efficiency unit does my EV use?
Tesla displays Wh/mi or Wh/km depending on region, most European brands quote kWh/100km, and North American reviews often use mi/kWh. All are interchangeable — convert once and you can compare any two cars directly.
Is a higher or lower number better?
For consumption units (Wh/km, kWh/100km, Wh/mi, kWh/100mi) lower is better — you use less energy per distance. For efficiency units (km/kWh, mi/kWh) higher is better — you drive further per unit of energy.
Can I share a conversion?
Yes. The Share button builds a link with your value and unit encoded as URL parameters. Anyone who opens it sees your conversion and, when battery capacity is included, the range it implies — no data ever leaves the browser.
Related calculators
- EV Efficiency Calculator
Work out your real-world efficiency from battery capacity, state of charge and distance travelled.
- EV Range Calculator
Estimate how far you can drive between two charge levels, in kilometres or miles.
Guides
- What Is EV Efficiency? kWh/100km, Wh/km and mi/kWh Explained
The units behind EV efficiency, what a good figure looks like, and how to measure your own.
- How to Calculate EV Range: A Practical Guide
The simple maths behind range estimates, with worked examples and winter adjustments.