Quick Answer: Watt-hours per mile to Watt-hours per kilometre
One watt-hour per mile equals 0.621371192 watt-hours per kilometre (1 Wh/mi = 0.621371192 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. Calculations use full-precision constants; displayed values are rounded to at most 9 significant figures. Results are rounded for display only. 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 and says so explicitly.
Each factor is exact by definition, derived from exact definitions, or a documented conventional value — see the methodology and sources.
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 Wh/mi | 124.274 | 200 Wh/km = 321.869 Wh/mi |
| 220 Wh/mi | 136.702 | 220 Wh/km = 354.056 Wh/mi |
| 240 Wh/mi | 149.129 | 240 Wh/km = 386.243 Wh/mi |
| 250 Wh/mi | 155.343 | 250 Wh/km = 402.336 Wh/mi |
| 260 Wh/mi | 161.557 | 260 Wh/km = 418.429 Wh/mi |
| 280 Wh/mi | 173.984 | 280 Wh/km = 450.616 Wh/mi |
| 300 Wh/mi | 186.411 | 300 Wh/km = 482.803 Wh/mi |
| 320 Wh/mi | 198.839 | 320 Wh/km = 514.99 Wh/mi |
| 350 Wh/mi | 217.48 | 350 Wh/km = 563.27 Wh/mi |
| 400 Wh/mi | 248.548 | 400 Wh/km = 643.738 Wh/mi |
| 500 Wh/mi | 310.686 | 500 Wh/km = 804.672 Wh/mi |
Frequently Asked Questions
Related Guides & Articles
View allMetric vs Imperial: The Complete Guide to Measurement Systems
The world is divided between two major measurement systems: metric and imperial. Understanding the d...
The Fascinating History of Temperature Scales
Temperature is something we experience every day, yet the scales we use to measure it have fascinati...
The International System of Units (SI): The Language of Science
The International System of Units (SI) is the modern metric system and the world most widely used sy...
The Complete Guide to Unit Conversion: From Basics to Mastery
Unit conversion is the essential skill that bridges the gap between different measurement systems. W...
Want to learn more about energy conversions?
Browse all energy articles →People Also Convert
Related calculators users frequently visit alongside watt-hours per mile to watt-hours per kilometre.
Conversion factors on this page are either exact by definition, derived from exact definitions, or conventional values in documented use. Each is listed with its source in our conversion methodology and sources, which cites the BIPM SI Brochure, NIST Special Publication 811 and the relevant IEC or national standards. Results are rounded for display only; calculations use full precision.