Unit converter
EV efficiency.
Convert Wh/mi to Wh/km, or pick any of the 4 units in the menus. Type in either box and the other follows. How much energy a vehicle spends per unit distance. Like fuel economy, miles per kilowatt-hour runs the opposite way to watt-hours per mile.
| Wh/mi | Wh/km |
|---|---|
| 1 Wh/mi | 0.621371 Wh/km |
| 2 Wh/mi | 1.24274 Wh/km |
| 3 Wh/mi | 1.86411 Wh/km |
| 4 Wh/mi | 2.48548 Wh/km |
| 5 Wh/mi | 3.10686 Wh/km |
| 10 Wh/mi | 6.21371 Wh/km |
| 15 Wh/mi | 9.32057 Wh/km |
| 20 Wh/mi | 12.4274 Wh/km |
| 25 Wh/mi | 15.5343 Wh/km |
| 50 Wh/mi | 31.0686 Wh/km |
| 75 Wh/mi | 46.6028 Wh/km |
| 100 Wh/mi | 62.1371 Wh/km |
| 250 Wh/mi | 155.343 Wh/km |
| 500 Wh/mi | 310.686 Wh/km |
| 1000 Wh/mi | 621.371 Wh/km |
- Every unit in the menus is defined against Wh/km, so any pairing converts by the same single route.
Definitions
- Watt-hours per mile is the same measure over the longer US mile, so the number is about 1.6 times larger for the same car.
- Watt-hours per kilometre measures how much energy a vehicle uses to travel: lower is better. A small EV manages about 150 Wh/km.
- Consumption in Wh/km rises as efficiency falls; mi/kWh moves in the opposite direction. This reciprocal relationship is the electric-vehicle equivalent of fuel economy.
- Every unit in the menus is exact by definition, so the only rounding on this page is the one you choose for the display.
How it works
Every value is converted into watt-hours per kilometre and then back out into the unit you asked for. One route covers every pairing in the menus, so an unusual combination is no less accurate than a common one, and adding a unit affects only that unit.
Both boxes are live. Whichever one you last typed in is the source, changing either menu recalculates straight away, and Swap exchanges the units and the values so the number you are reading stays where you are looking.
Display precision limits significant figures rather than decimal places, which matters here because a reciprocal magnifies rounding: a figure trimmed at one end of the scale moves further at the other. Only the display is rounded. The editable box always holds a plain number at full working precision, so you can carry on from either side.
Common questions this answers: how many watt-hours per kilometre in a watt-hour per mile (0.621371), how many watt-hours per mile in a watt-hour per kilometre (1.60934), and what 250 Wh/mi is in watt-hours per kilometre (155.343 Wh/km).
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