EV Efficiency Converter

Instantly convert between all common electric vehicle efficiency units.

What this calculator does

Convert EV efficiency between common units like mi/kWh, kWh/100mi, Wh/mi, MPGe, kWh/100km, Wh/km, and km/kWh. The converter helps you compare vehicle labels, dashboards, and international units using one consistent input value.

Inputs explained

Input value: The efficiency number you want to convert.
Input unit: Select the unit that matches your value.

How it works / Method

Normalize your input to a base unit of kWh per 100 km.
Convert the base value to every other unit using standard constants.
Display the converted values with appropriate rounding.

Formula(s) used

1 mile = 1.609344 km

kWh_per_100mi = 100 / (mi_per_kWh)

kWh_per_100km = 100 / (km_per_kWh)

Wh_per_mi = kWh_per_mi * 1000

MPGe = 33.7 * mi_per_kWh

Conversions are purely mathematical and do not change real world efficiency.

Input

Conversions

mi/kWh (Range per Energy)	-
kWh/100mi (Consumption)	-
Wh/mi	-
MPGe (EPA)	-
km/kWh	-
kWh/100km	-
Wh/km	-

Step-by-step example

Example input: 3.5 mi/kWh.

kWh/100mi: 100 / 3.5 = 28.57 kWh/100mi.
kWh/100km: 100 / (3.5 * 1.609344) = 17.75 kWh/100km.
Wh/mi: (1 / 3.5) * 1000 = 285.7 Wh/mi.
Wh/km: 285.7 / 1.609344 = 177.5 Wh/km.
MPGe: 33.7 * 3.5 = 118.0 MPGe.

Use cases

Compare EVs listed in different regions and unit systems.
Translate dashboard efficiency into kWh/100km for trip planning.
Convert MPGe to energy per distance for cost calculations.
Standardize data when building EV spreadsheets or reports.
Match EPA ratings with real world efficiency numbers.
Switch between Wh/mi and kWh/100mi quickly.

Assumptions & limitations

Conversions assume the standard mile to kilometer constant.
MPGe uses the EPA definition of 33.7 kWh per gallon equivalent.
Rounding can introduce small differences between units.
This tool does not estimate range or cost by itself.
Efficiency can vary with driving conditions, even if units match.
Results are for comparison, not certification.

Disclaimer: Results are estimates for planning only. Always use manufacturer or test data for official reporting.

Frequently Asked Questions

What is MPGe and why does it use 33.7 kWh?

MPGe stands for miles per gallon equivalent. The U.S. EPA defines one gallon of gasoline as containing 33.7 kWh of energy, so MPGe compares how far an EV can travel on that amount of electricity. A higher MPGe means the EV uses less energy per mile. This conversion allows EVs and gasoline vehicles to be compared on a common energy basis.

Which unit is best for comparing EVs?

Many analysts prefer energy per distance units such as kWh/100km or kWh/100mi because lower values clearly indicate better efficiency. Others prefer mi/kWh because higher values feel intuitive. The best unit is the one you understand and use consistently. This converter lets you see all views at once so comparisons are easy regardless of the original unit.

Why does higher mi/kWh mean lower kWh/100mi?

mi/kWh measures distance per unit of energy, while kWh/100mi measures energy used per distance. They are inverses of each other. If you go farther on one kWh, you use less energy to travel 100 miles, so kWh/100mi gets smaller. The converter handles this inversion automatically so you do not need to do manual calculations.

Can I convert from Wh/mi or Wh/km?

Yes. Wh/mi and Wh/km are common on vehicle dashboards and apps. The converter simply divides or multiplies by 1000 to move between Wh and kWh, then applies the distance conversion if needed. This lets you move between Wh based displays and kWh based planning tools without mistakes.

Does converting units change real world efficiency?

No. Unit conversion only changes the way the number is expressed. Your actual energy use per mile or kilometer is the same regardless of units. Use the conversion to compare with labels or apps, but remember that real world efficiency still varies with speed, weather, and terrain.

How can I use these results for cost estimates?

Convert to kWh/100mi or kWh/100km, then multiply by your electricity price per kWh. That gives energy cost per 100 miles or 100 km. You can also convert to kWh per mile and multiply by trip distance for total energy. For charging losses and public pricing, use the charging cost calculator for a more complete estimate.

Sources & references

U.S. EPA: Fuel economy and EV range testing - Defines MPGe and the 33.7 kWh per gallon equivalent.
U.S. DOE: MPGe fact of the week - Explains MPGe as an energy equivalence.
U.S. Energy Information Administration: Measuring electricity - Defines kW and kWh units used in EV efficiency.
Schema.org: FAQPage, WebPage, and BreadcrumbList - Structured data definitions used on this page.