EV Efficiency Converter

Last updated: June 2026

Efficiency value

miKwh

From unit

Miles per kWh

4 mi/kWh

kWh per 100km

15.53 kWh/100km

kWh per 100 miles

25 kWh/100mi

MPGe

134.8 MPGe

Running cost comparison

Electricity price

p/kWh

Petrol price

p/L

Petrol economy

UK mpg

EV cost per mile

EV cost per 100 miles

£7

Petrol cost per 100 miles

£14.65

Formula

kWh/100km = 100 / (miles per kWh x 1.60934). MPGe = miles per kWh x 33.7. EV pence per mile = electricity pence per kWh / miles per kWh.

Common EV efficiency reference

Car	mi/kWh	kWh/100km
Tesla Model 3	4.5	14.0
Nissan Leaf	3.5	18.0
VW ID.4	3.8	16.2
BMW iX3	3.7	16.6
Renault Zoe	3.6	17.0

About this calculator

EV Efficiency Converter helps you convert miles per kWh, kWh per 100km, kWh per 100 miles, or MPGe to equivalent EV efficiency units quickly without doing the arithmetic by hand. It is designed for everyday checks where a clear answer matters: EV range comparisons, UK and EU EV listings, home charging cost checks, petrol versus EV running cost estimates. Enter a number in either side of the converter, use the swap button when you want to reverse direction, then compare the result with the quick reference table. Real EV efficiency changes with temperature, speed, tyres, terrain, battery condition, and driving style. Treat cost comparison results as estimates.

EV Efficiency Converter formula

The calculator applies a fixed unit conversion factor. For bidirectional conversion, the reverse formula uses the same factor in the opposite direction.

kWh/100km = 100 / (miles per kWh x 1.60934); MPGe = miles per kWh x 33.7
miles per kWh = 62.1371 / kWh per 100km; miles per kWh = MPGe / 33.7

How to use the ev efficiency converter

Type the miles per kWh, kWh per 100km, kWh per 100 miles, or MPGe value into the first input.
Read the converted equivalent EV efficiency units value in the second input.
Type into the second input if you want to convert in the opposite direction.
Use the swap button to change which unit appears first.
Check the formula display if you need to show your working.
Use the reference table for common values without repeated typing.

Worked examples

Example conversion

Input: 4 mi/kWh

Calculation: 4 mi/kWh = 100 / (4 x 1.60934) = 15.53 kWh/100km

Result: 15.53 kWh/100km

Second example

Input: 3.5 mi/kWh x 33.7

Calculation: 3.5 mi/kWh x 33.7 = 117.95 MPGe

Result: 117.95 MPGe

When this conversion is useful

Use this converter when information is given in miles per kWh, kWh per 100km, kWh per 100 miles, or MPGe but your form, plan, recipe, product listing, or comparison needs equivalent EV efficiency units. It is especially useful when mixing UK, metric, and imperial measurements.

EV range comparisons: Enter the source value, check the converted result, and keep enough decimal places for the level of precision needed.
UK and EU EV listings: Enter the source value, check the converted result, and keep enough decimal places for the level of precision needed.
Home charging cost checks: Enter the source value, check the converted result, and keep enough decimal places for the level of precision needed.
Petrol versus EV running cost estimates: Enter the source value, check the converted result, and keep enough decimal places for the level of precision needed.

Rounding and precision

The live converter keeps useful decimal precision, while the reference table rounds values for readability. For casual use, rounded values are usually enough. For engineering, legal documents, medical records, building work, or purchase specifications, keep the original units and confirm the required precision before relying on a rounded number.

Common mistakes

Rounding too early and then using the rounded number in another calculation.
Mixing UK imperial and US customary units where they are not the same.
Entering a combined value in one field when the calculator expects separate units.
Copying a result without the unit label.
Using an approximate mental conversion when an exact factor is needed.

Conversion disclaimer

This converter is for general information and everyday calculation support. It does not replace professional measurement, medical, engineering, legal, or product-specific guidance where exact tolerances matter.

Reference table values may be rounded.
Source measurements can be approximate before they reach the calculator.
Some industries require specific rounding rules or certified measuring equipment.

Frequently asked questions

What is the formula for the ev efficiency converter?

Use kWh/100km = 100 / (miles per kWh x 1.60934); MPGe = miles per kWh x 33.7. To convert back, use miles per kWh = 62.1371 / kWh per 100km; miles per kWh = MPGe / 33.7.

Can I type in either input?

Yes. The converter is bidirectional, so changing either input updates the other side.

Why does my result have decimals?

Many unit conversions do not produce a whole number. Decimals keep the result more accurate than rounding to the nearest whole unit.

Should I round the answer?

For everyday use, rounding to one or two decimals is often fine. For technical work, keep more decimal places and follow the rounding rule required for that task.

Are UK and US units always the same?

No. Some units, especially gallons and fluid ounces, differ between UK imperial and US customary systems. Use the converter that matches the system you need.

Related calculators

EV Charging Cost Calculator
EV vs Petrol Cost Calculator
Fuel Economy Converter

What does this mean?

This calculator is designed to help you understand the likely number before you make a decision or start an application.

Your result should be checked against official UK guidance, especially if your circumstances include dependants, exemptions, prior leave, or a complex immigration history.

Treat the figure as a planning tool rather than legal advice. Where the answer affects an application deadline or major payment, speak to an authorised adviser.