EV Efficiency Converter
Enter any electric-car efficiency figure and instantly see it in every unit — MPGe, kWh/100km, kWh/100mi, Wh/mi, Wh/km, mi/kWh and km/kWh. The converter grades it A–F, translates EPA, WLTP and NEDC ratings, models real-world cold-weather and highway losses, and ranks your number against 90 real EVs. Remember: for mi/kWh and MPGe higher is better; for Wh/mi and kWh/100km lower is better.
Your efficiency
How many miles you travel on one kilowatt-hour. The most intuitive unit — higher is better.
Every unit, live
Very good — typical for a mainstream EV. Real-world range will track the battery size closely.
What it means: a 75 kWh battery at 3.50 mi/kWh delivers about 263 miles of range, and at $0.17/kWh costs roughly $0.049/mile to drive. Common mistake: assuming a lower number is always worse — for mi/kWh, higher is the good direction.
This beats 47% of the 90 EVs in our database. Scroll to the ranking to see exactly which cars match it — then feed the number into the Charging Cost Calculator to turn it into money.
Real-world conditions
The window-sticker figure is a lab number. Set your conditions to see your true on-road efficiency.
Rated vs real-world
Your conditions use about 0% more energy than the lab figure.
The same car under EPA, WLTP & NEDC
If your figure is realistic (EPA-style), this is how the showroom sticker would read under each test cycle. WLTP and NEDC look better because their cycles are gentler.
| Standard | MPGe | mi/kWh | kWh/100km | Notes |
|---|---|---|---|---|
| EPA (US) | 118 | 3.50 | 17.8 | Closest to real-world; includes highway speed, AC and cold starts. |
| WLTP (EU) | 131 | 3.89 | 16.0 | Current European cycle — typically ~10% optimistic vs real-world. |
| NEDC (old) | 147 | 4.38 | 14.2 | Obsolete European cycle — often 20–30% optimistic. Phased out 2018. |
How 90 real EVs rank — and where yours sits
Sorted most-to-least efficient. Your 3.50 mi/kWh beats 47% of them. Bars relative to the class leader.
Conversion formulas
| From | To | Formula | Example |
|---|---|---|---|
| mi/kWh | Wh/mi | 1000 ÷ mi/kWh | 4 → 250 |
| mi/kWh | MPGe | mi/kWh × 33.7 | 4 → 135 |
| mi/kWh | km/kWh | mi/kWh × 1.60934 | 4 → 6.44 |
| MPGe | Wh/mi | 33,700 ÷ MPGe | 120 → 281 |
| Wh/mi | kWh/100km | Wh/mi × 0.621371 ÷ 10 | 250 → 15.5 |
| kWh/100km | mi/kWh | 1000 ÷ (kWh/100km × 16.0934) | 18 → 3.45 |
| Wh/km | Wh/mi | Wh/km × 1.60934 | 155 → 249 |
Quick reference: mi/kWh in every unit
| mi/kWh | km/kWh | MPGe | Wh/mi | Wh/km | kWh/100km |
|---|---|---|---|---|---|
| 2.0 | 3.22 | 67 | 500 | 311 | 31.1 |
| 2.5 | 4.02 | 84 | 400 | 249 | 24.9 |
| 3.0 | 4.83 | 101 | 333 | 207 | 20.7 |
| 3.5 | 5.63 | 118 | 286 | 178 | 17.8 |
| 4.0 | 6.44 | 135 | 250 | 155 | 15.5 |
| 4.5 | 7.24 | 152 | 222 | 138 | 13.8 |
| 5.0 | 8.05 | 169 | 200 | 124 | 12.4 |
Why this converter exists
Electric cars suffer from a Tower-of-Babel problem. A Tesla owner in Texas reads 250 Wh/mi on the dash; a reviewer in Germany quotes 16 kWh/100km; the EPA window sticker says 132 MPGe; and a driver in Mumbai watches 7 km/kWh tick by — and these are all the same efficiency. When a buyer tries to compare a US review against a European one, or read their own trip computer against a spec sheet, the units simply don’t line up. This tool exists to make every EV efficiency figure speak the same language instantly.
The unit that trips people up most is MPGe. The US EPA created it so shoppers could compare an EV to a petrol car on the familiar miles-per-gallon scale. It fixes the energy in one gallon of petrol at 33.7 kWh, so MPGe = mi/kWh × 33.7. The catch is direction: MPGe, mi/kWh and km/kWh are “more is better,” while Wh/mi, Wh/km and kWh/100km are “less is better.” Mixing the two is how a genuinely efficient car gets mistaken for a thirsty one. Every readout here is labelled with its good direction to kill that confusion.
Then there’s the test-cycle gap. The same car is rated under different procedures in different markets: EPA in the US, WLTP in Europe (since 2018), and the obsolete NEDC that lingered on older listings. EPA is the most realistic; WLTP reads roughly 10% more optimistic, and NEDC 20–30% more. That’s why a car’s European range looks bigger than its American one — not because it changed, but because the ruler did. The standards panel above translates between them so you compare like with like.
Finally, no lab figure survives contact with a real road. Cold weather can cut efficiency 20–40%, motorway speed adds about 20% from aerodynamic drag, hills and headwinds add more, and cabin heating draws a steady tax. The real-world simulator applies these factors so you see the number you’ll actually live with — and the A–F grade and 90-car ranking put it in context. Conversions use the EPA 33.7 kWh/gallon basis and exact distance factors; the standard and real-world adjustments are research-based averages. Reviewed twice a year.
How to use this converter
- 1Type your efficiency value into the converter — for example 3.5.
- 2Choose what that number is: mi/kWh, km/kWh, MPGe, kWh/100km, kWh/100mi, Wh/mi or Wh/km.
- 3Read the live grid — your figure appears in all seven units, each labelled with its good direction, plus an A–F grade.
- 4Set real-world conditions (cold, highway, hilly, climate control) to see your true on-road efficiency.
- 5Open the standards panel to translate the same car between EPA, WLTP and NEDC.
- 6Scroll the 90-EV ranking to see exactly which cars match your number, then send it to the Charging Cost Calculator.
Trusted by EV drivers, reviewers & fleets
“I review cars for a German outlet and constantly translate US Wh/mi figures into kWh/100km for my readers. This does all seven units at once and even flags the EPA-vs-WLTP gap — it has replaced my spreadsheet entirely.”
“My trip computer shows km/kWh but every YouTube review uses MPGe. Now I can compare instantly, and the A–F grade told me my real-world 7 km/kWh is genuinely good. The cold-weather toggle was a nice reality check too.”
“The 90-car ranking is gold for procurement. I can drop in a target Wh/mi and instantly see which models clear the bar across regions. Clean, fast, and the real-world simulator makes the business case honest.”
“Finally understood what my CLTC number means in real units. Converting to MPGe and seeing where the SU7 ranks against US EVs was eye-opening — and the highway-speed factor explained my motorway battery drain perfectly.”
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Last reviewed June 2026 · Conversions use the EPA 33.7 kWh/gallon equivalent and 1 mi = 1.60934 km. Standard & real-world factors are research-based estimates.