How to Compare the Real Energy Cost of an Electric Car

Electric vehicles are usually rated in MPGe (miles per gallon equivalent), but MPGe doesn’t tell you how much electricity you actually use — or how much it costs to drive. To compare EVs properly, you need to convert those ratings into real energy and cost-per-mile numbers.

This guide shows how to do that.

None — just a calculator or the reference tool above.

MPGe is a government-defined unit that compares electricity to gasoline by assuming:

33.7 kilowatt-hours (kWh) = the energy in one gallon of gasoline

So if an EV is rated at 100 MPGe, it uses the same amount of energy as a gasoline car that gets 100 miles per gallon — but that doesn’t tell you how much electricity it consumes.

To see how efficiently an EV uses electricity, use this formula:

Miles per kWh=MPGe33.7\text{Miles per kWh} = \frac{\text{MPGe}}{33.7}Miles per kWh=33.7MPGe​Example:

If an EV is rated at 101 MPGe:

101÷33.7≈3.0 miles per kWh101 ÷ 33.7 ≈ 3.0 \text{ miles per kWh}101÷33.7≈3.0 miles per kWhThat means the vehicle travels about 3 miles on one kWh of electricity.

This number is far more useful than MPGe because it:

1. Matches how electricity is billed
2. Lets you estimate charging cost
3. Allows EV-to-EV comparison

Once you know miles per kWh, you can estimate driving cost:

Cost per mile=Electricity price per kWhMiles per kWh\text{Cost per mile} = \frac{\text{Electricity price per kWh}}{\text{Miles per kWh}}Cost per mile=Miles per kWhElectricity price per kWh​Example:

If electricity costs $0.15/kWh and your EV gets 3 mi/kWh:

0.15÷3=5 cents per mile0.15 ÷ 3 = 5 \text{ cents per mile}0.15÷3=5 cents per mileThat’s usually much cheaper than driving a gasoline vehicle.

Gas cars are rated in MPG.

EVs are rated in MPGe.

By converting both into cost per mile, you can directly compare:

1. Electric cars
2. Hybrids
3. Gas vehicles

This avoids misleading comparisons based on sticker numbers alone.

You can do all these conversions by hand, but it’s easier to use a calculator that applies the same formulas automatically.

This tool converts:

1. MPGe → mi/kWh
2. kWh → cost per mile
3. EVs → gas-equivalent cost

https://carleasetips.com/ev-efficiency-converter/

It uses the standard 33.7 kWh energy equivalence and lets you plug in your local electricity price.

MPGe is useful for regulations.

Cost per mile and kWh per mile show what you actually pay.

When you convert EV ratings into real energy units, you get:

1. Honest cost comparisons
2. Better lease and purchase decisions
3. A clearer picture of efficiency