Quick Answer: Watt-hours per mile to Watt-hours per kilometre
One watt-hour per mile equals 0.621371 watt-hours per kilometre (1 Wh/mi = 0.621371 Wh/km).
Conversely, 1 Wh/km = 1.609344 Wh/mi.
Formula: Wh/km = Wh/mi ÷ 1.609344
Worked examples
- 200 Wh/mi = 124.274238 Wh/km
- 220 Wh/mi = 136.701662 Wh/km
- 240 Wh/mi = 149.129086 Wh/km
Method and limitations
Energy per unit distance scales inversely with the distance unit. Because one mile is 1.609344 km, energy spent per mile is spread over more kilometres, so divide Wh/mi by 1.609344 to get Wh/km. Displayed values are rounded to a maximum of 6 significant decimals. Results are rounded for readability. Full precision is kept internally, so long chains of conversions do not accumulate rounding error. Where US customary and imperial units share a name (for example fluid ounces and gallons), this page uses the US customary definition.
Last updated: April 2026. Conversion factors follow internationally defined standards.
Conversion Formula
Energy per unit distance scales inversely with the distance unit. Because one mile is 1.609344 km, energy spent per mile is spread over more kilometres, so divide Wh/mi by 1.609344 to get Wh/km.
Complete Guide to Watt-hours per mile to Watt-hours per kilometre Conversion
What is a Watt-hours per mile?
Watt-hours per mile (Wh/mi) is the EV efficiency unit used on US trip computers and EPA range figures.
What is a Watt-hours per kilometre?
Watt-hours per kilometre (Wh/km) is the metric equivalent, and the basis for the kWh/100 km figure quoted in Europe under WLTP.
How the Conversion Works
Divide the Wh/mi figure by the exact factor 1.609344. Dividing the result by 10 again gives kWh/100 km, so a single conversion covers both the US and European way of describing EV efficiency.
Why This Conversion Matters
EV range, home charging cost and per-kilometre running cost all follow from consumption. Comparing a US review (Wh/mi) with a European spec sheet (kWh/100 km) is impossible until both are expressed in the same unit.
Scientific Context
The mile-to-kilometre relationship has been exactly 1.609344 since the 1959 international yard and pound agreement, so this conversion introduces no rounding error of its own.
Step-by-Step Conversion Guide
Follow these steps to convert watt-hours per mile to watt-hours per kilometre manually:
Start with your value in watt-hours per mile
Example: You want to convert 240 Wh/mi
Apply the conversion formula
Use the formula: Wh/km = Wh/mi ÷ 1.609344
Calculate the result
240 Wh/mi = 149.1291 Wh/km
Verify your answer
Use our calculator above to double-check your manual calculation.
Quick Mental Math Tip
Energy per unit distance scales inversely with the distance unit. Because one mile is 1.609344 km, energy spent per mile is spread over more kilometres, so divide Wh/mi by 1.609344 to get Wh/km.
Common Conversions
| Watt-hours per mile (Wh/mi) | Watt-hours per kilometre (Wh/km) | Watt-hours per kilometre → Watt-hours per mile |
|---|---|---|
| 200 | 124.2742 | 200 Wh/km = 321.8688 Wh/mi |
| 220 | 136.7017 | 220 Wh/km = 354.0557 Wh/mi |
| 240 | 149.1291 | 240 Wh/km = 386.2426 Wh/mi |
| 250 | 155.3428 | 250 Wh/km = 402.336 Wh/mi |
| 260 | 161.5565 | 260 Wh/km = 418.4294 Wh/mi |
| 280 | 173.9839 | 280 Wh/km = 450.6163 Wh/mi |
| 300 | 186.4114 | 300 Wh/km = 482.8032 Wh/mi |
| 320 | 198.8388 | 320 Wh/km = 514.9901 Wh/mi |
| 350 | 217.4799 | 350 Wh/km = 563.2704 Wh/mi |
| 400 | 248.5485 | 400 Wh/km = 643.7376 Wh/mi |
| 500 | 310.6856 | 500 Wh/km = 804.672 Wh/mi |
Frequently Asked Questions
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Last verified: April 2026. All conversion factors are based on internationally defined standards.