How to use the ev efficiency unit converter
- Enter an efficiency value and pick its unit from the list.
- Open the advanced box only if you need a different kWh per gallon equivalent for MPGe.
- Read the same efficiency in the other six units.
- Remember the direction: miles per kWh and MPGe go up when a car is more efficient, while the energy per distance units go down.
Formula
km per kWh = miles per kWh x 1.609344
kWh per 100 miles = 100 / (miles per kWh)
kWh per 100 km = 100 / (miles per kWh x 1.609344)
Wh per mile = 1000 / (miles per kWh)
MPGe = miles per kWh x 33.705
One mile is exactly 1.609344 km. The 33.705 kWh per gallon equivalent is the figure used in MPGe, and you can change it in the advanced box if your source uses another value.
A car that travels 3.5 miles per kWh
3.5 miles per kWh equals 5.633 km per kWh. The energy per distance forms are 100 / 3.5 = 28.571 kWh per 100 miles, 17.753 kWh per 100 km, 285.7 Wh per mile and 177.5 Wh per km.
In MPGe it is 3.5 x 33.705 = 118. Going the other way, 17 kWh per 100 km is 100 / (17 x 1.609344) = 3.655 miles per kWh, and 110 MPGe is 3.264 miles per kWh.
Two families of units
Distance per energy units, like miles per kWh, are like fuel economy in miles per gallon: higher is better. Energy per distance units, like kWh per 100 km, are like fuel use in liters per 100 km: lower is better. Because they are reciprocals, a small change in a low kWh per 100 km number matches a larger change in miles per kWh than the same change at a high number.
What the numbers include
Published efficiency figures may measure energy at the wall, at the battery or at the wheels, and each gives a different number for the same car. Check what your source measures before comparing two figures. To turn efficiency into money, see the EV Charging Cost Calculator and the EV vs Gas Cost Calculator, and for fuel cars the MPG Calculator.
Assumptions and limits
- One mile is 1.609344 kilometers exactly.
- MPGe uses 33.705 kWh per gallon equivalent unless you change it.
- The conversions are exact arithmetic on the number you enter. They do not add charging losses.
- Values must be above zero.
Frequently asked questions
What is MPGe?
It is miles per gallon equivalent, a way to compare an electric car with a gasoline car by treating 33.705 kWh of electricity as the energy in a gallon of gasoline.
Why is a lower kWh per 100 km better?
It means the car uses less energy to travel the same distance. A car at 15 kWh per 100 km is more efficient than one at 20.
Can I convert to liters per 100 km?
Not directly, because that unit measures liquid fuel. MPGe is the closest comparison, and the page gives it so that you can compare with a fuel economy figure.
Why change the kWh per gallon value?
Some sources use slightly different energy values for a gallon of fuel. The advanced box lets you match the figure your source uses so the MPGe results line up.