How do you convert MPGe to kWh per 100 miles?

Divide 3,370 by the MPGe figure. The constant comes from the EPA definition that one gallon of gasoline is energy-equivalent to 33.7 kilowatt-hours, so 33.7 multiplied by 100 gives 3,370. A car rated at 100 MPGe therefore uses 33.7 kWh per 100 miles, and one rated at 120 MPGe uses 3370 divided by 120, or 28.1 kWh per 100 miles. The relationship is inverse: higher MPGe means lower kWh per 100 miles.

What is MPGe and why does it exist?

MPGe stands for miles per gallon of gasoline equivalent. It exists so that an electric car can appear on the same window sticker scale as a petrol car, by converting electricity into the amount of petrol holding the same energy. It is a comparison device rather than a physical measurement, and it says nothing about what the electricity costs you or how much of your battery a trip will use. For those questions, kWh per 100 miles or Wh per mile are the more direct units.

What is the difference between Wh/mi and kWh/100mi?

They are the same measurement at different scales, so converting between them is only a factor of ten. Multiply kWh per 100 miles by 10 to get watt-hours per mile: 33.7 kWh/100mi is 337 Wh/mi. Wh/mi is what most in-car displays show in the United States because it updates meaningfully over a short drive, while kWh/100mi is the unit used on EPA window stickers because it lines up with the L/100km convention used elsewhere.

How many kWh per 100 miles is good for an EV?

For a modern electric sedan in mild weather, roughly 25 to 30 kWh per 100 miles is normal, which is about 112 to 135 MPGe. Crossovers and small SUVs typically land near 30 to 35, and electric pickups and vans often run 40 or more. The figure is not fixed for a given car: sustained high speed, cold weather and towing all push it up substantially, because aerodynamic drag rises with the square of speed and cabin heating draws real power.

How do I work out my own efficiency figure?

Divide the energy used by the distance covered over the same interval. If a drive consumed 18 kWh and covered 62 miles, that is 18 divided by 62, or 0.290 kWh per mile, which is 29.0 kWh per 100 miles and 290 Wh per mile. Use a GPS-measured distance rather than the car odometer if you want the number to be right, because a car odometer counts wheel rotations against a stored tyre circumference and typically reads 1 to 3 percent high, which flatters your efficiency.

EV efficiency converter

MPGe to kWh per 100 miles

Five ways of saying the same thing. Edit any field and the other four update live.

MPGe kWh per 100 mi Wh per mile miles per kWh kWh per 100 km

1 gal gasoline equivalent = 33.7 kWh (EPA) · 1 mile = 1.609344 km

The one constant behind all of it

Every conversion on this page comes from a single number: the EPA treats one US gallon of gasoline as energy-equivalent to 33.7 kilowatt-hours. That is the whole basis of MPGe. A car rated at 100 MPGe travels 100 miles on 33.7 kWh, which is why the default figures above line up so neatly.

From there the arithmetic is short. To go from MPGe to kWh per 100 miles, divide 3,370 by the MPGe figure. To go the other way, divide 3,370 by the kWh per 100 miles. The relationship is inverse, so a higher MPGe always means a lower kWh figure, and the two move in opposite directions as your driving changes.

Wh per mile is the same measurement shifted one decimal place: multiply kWh per 100 miles by ten. It is what most US in-car displays show, because over a short drive it moves by a readable amount rather than crawling.

Common figures side by side

MPGe	kWh/100mi	Wh/mi	mi/kWh	kWh/100km	Typically
140	24.1	241	4.15	15.0	Efficient compact EV, ideal conditions
130	25.9	259	3.86	16.1	Aerodynamic sedan, mixed driving
120	28.1	281	3.56	17.5	Typical modern sedan
110	30.6	306	3.26	19.0	Small crossover
100	33.7	337	2.97	20.9	Mid-size SUV, the round-number benchmark
90	37.4	374	2.67	23.3	Large SUV
80	42.1	421	2.37	26.2	Electric pickup or van
70	48.1	481	2.08	29.9	Heavy pickup, or any EV at sustained high speed
60	56.2	562	1.78	34.9	Towing, or cold weather with a large battery

Which unit to actually use

MPGe exists for one purpose: putting an electric car on the same window-sticker scale as a petrol one. It is a translation device, not a measurement. It cannot tell you what a trip costs, because electricity is not priced in gallons, and it cannot tell you how much of your battery a drive will consume.

For anything practical, kWh per 100 miles or Wh per mile is the unit you want. Both divide directly into your battery capacity, so a 65 kWh pack at 29 kWh/100mi gives roughly 224 miles, and the arithmetic is one step rather than three. Outside the United States, kWh/100km plays the same role and matches the familiar L/100km convention.

Miles per kWh is the odd one out. It is intuitive, since bigger is better, but it makes comparisons harder: the difference between 3.0 and 3.3 mi/kWh looks small and is actually a ten percent swing in consumption.

Why your real figure moves so much

A sticker number is a single value for something that is not a constant. The largest variable on a road trip is speed, because aerodynamic drag rises with the square of it. Measured fleet data puts an electric sedan at 226 miles of range at 70 mph and 200 at 80, a loss of 11.5 percent for the last 10 mph alone, and a van gives up considerably more.

That works out at roughly 29 kWh/100mi at 70 mph rising to about 32.5 at 80 for the same car. If you are planning around a sticker figure, you are planning around a number your motorway driving will not produce. We work through the physics and the fleet numbers in EV range vs speed, and the charging stop calculator turns it into an arrival time.

To measure your own figure, divide energy used by distance covered over the same interval. Use a GPS-measured distance rather than the dashboard: a car odometer counts wheel rotations against a stored tyre circumference and typically reads 1 to 3 percent high, as we cover in is your odometer accurate, and an inflated distance quietly flatters your efficiency. The GPS odometer gives the honest denominator.

EV charging stop calculator — how speed changes your arrival time
EV range vs speed — what 80 mph actually costs
MPG calculator — the petrol equivalent, four units
GPS odometer — measure distance independently of the car

← All tools

The one constant behind all of it

Common figures side by side

Which unit to actually use

Why your real figure moves so much

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