EV efficiency calculator: your real mi/kWh (and kWh per 100 km)

How to read the result

Your efficiency is simply the energy you used divided by the distance. Energy used is your usable battery size times the percentage of charge the trip consumed, so a 60 kWh battery down 50% is 30 kWh. Divide by the miles (or km) driven and you get your real consumption — the honest figure to set against the EPA/WLTP number. From it we also project how far a full charge would take you at the same rate. Cold weather, highway speed and climate control all push consumption up, so a winter highway run reads far higher than a mild city commute.

Frequently asked questions

How do I calculate mi/kWh (or kWh per 100 km)?

For mi/kWh, divide the miles you drove by the kWh you used. For kWh/100 km, divide the energy by the distance and multiply by 100. Read the energy from the car's trip computer, or estimate it as your usable battery size times the percentage of charge the trip used.

What is a good efficiency for an electric car?

Most EVs run about 3–4 mi/kWh (roughly 15–22 kWh/100 km) in real use. Small, aerodynamic cars in the city can beat 4 mi/kWh; large SUVs, highway speeds and cold weather drop below 3. Your own number matters more than any average — track it across the seasons.

Why is my efficiency worse than the rated figure?

Rated numbers are measured in mild, gentle lab conditions. Real driving — cold, fast roads, heating and climate control — uses more energy, so real consumption 10–40% higher is normal. Compare your result with the spec figure to see your personal gap.

Should I use the battery percentage or the trip computer?

Both work. The trip computer's kWh reading is the most direct; without it, the battery-percentage method (usable battery size × percent used) is a good estimate. For the cleanest reading, measure over a longer trip and avoid part-charges midway.