For EV Owners

EV Efficiency
Calculator

Is your EV consumption good or bad?
Switch between US (Wh/mi) and Europe (Wh/km) modes to calculate costs and gas savings.

⚡️
Rank S
Eco Master
Wh/km
Excellent Poor

▼ Analysis Results

Metric Equivalent
6.02km/kWh
🚗 Equivalent to Model Y / ID.4
B
Average

💰 Gas Car Comparison

Comparing fuel costs to a gas car:

4.9 L/100km

Equivalent fuel consumption.

(Based on: 0.30/kWh, Gas 1.80/L)

Cost per km
€0.05
Alt Unit
16.6 kWh/100km
MPGe (US)
124 MPGe
Copied!

⚙️ Simulation Settings

€/kWh
€/L
kWh
Est. Range (100%): Approx. 360 km
BMI Calculator Class Year Age Chart Character Counter

EV Efficiency Guide

US vs European Standards Explained

Unit Confusion: Wh/mi vs Wh/km

Depending on where you live or what car you drive, the efficiency number on your dashboard might look very different.

🇪🇺 Europe / World (Wh/km)

Watt-hours per kilometer

Standard for Tesla in Europe, Australia, and Asia.
Lower is better.
• Excellent: < 140 Wh/km
• Average: 160-180 Wh/km

🇺🇸 USA (Wh/mi)

Watt-hours per mile

Standard for Tesla in North America.
Lower is better.
Since a mile is longer than a km (1.6x), the numbers are higher.
• Excellent: < 230 Wh/mi
• Average: 250-300 Wh/mi

What is MPGe?

MPGe (Miles Per Gallon equivalent) is a US standard created to help gas car drivers understand EV efficiency. It converts electricity usage into "gallons of gas energy."
33.7 kWh of electricity contains roughly the same energy as 1 gallon of gasoline. If your EV can travel 100 miles on 33.7 kWh, it gets 100 MPGe.

Winter Range Loss

Whether you are in the US or Europe, cold weather impacts EVs significantly. Expect a 20-30% range drop when temperatures fall below freezing (0°C / 32°F) due to cabin heating and reduced battery chemistry performance.

How to Use the EV Efficiency Calculator

Convert your dashboard number and see what each mile or kilometer really costs.

Calculate your EV efficiency in 3 steps

  1. Choose USA (Wh/mi, gallons, $) or Europe / Global (Wh/km, liters, €).
  2. Type the efficiency shown on your car's trip meter or app, or drag the slider.
  3. Enter your electricity price, local gas price, and battery size to see your cost per mile or km, the matching gas mileage, and your estimated range.

The calculator instantly converts your number into km/kWh, mi/kWh, kWh/100km, kWh/100mi, and MPGe, and gives you a simple efficiency rank so you can tell at a glance whether your driving is excellent, average, or energy hungry.

EV efficiency conversion formulas

All EV efficiency units describe the same thing: how much electricity it takes to cover a distance. Use these formulas if you want to check the math yourself.

FromToFormula
Wh/miWh/kmWh/mi ÷ 1.609
Wh/kmWh/miWh/km × 1.609
Wh/mimi/kWh1,000 ÷ Wh/mi
Wh/kmkWh/100kmWh/km ÷ 10
Wh/miMPGe33,705 ÷ Wh/mi
kWh/100miMPGe3,370.5 ÷ kWh/100mi

Example: an EV that uses 250 Wh/mi gets 4.0 mi/kWh, which is about 155 Wh/km, 15.5 kWh/100km, or roughly 135 MPGe.

What is good EV efficiency?

Lower Wh/mi or Wh/km means a more efficient car. The calculator ranks your number on this scale, based on real-world mixed driving in mild weather.

RankWh/kmWh/mimi/kWhWhat it usually means
SS – Alien Tech100 or less161 or less6.2+Hypermiling or very slow, warm-weather driving
S – Eco Master101–130162–2094.8–6.2Efficient sedans in city or suburban driving
A – Excellent131–160210–2573.9–4.8Most compact EVs and crossovers in mixed driving
B – Average161–190258–3063.3–3.9Larger SUVs, performance trims, or lots of highway miles
C – HeavyOver 190Over 306Under 3.3Electric pickups, three-row SUVs, towing, or winter driving

How to calculate EV cost per mile

Multiply your efficiency in kWh per mile by your electricity price. At 250 Wh/mi (0.25 kWh/mi) and a home rate of $0.16/kWh, each mile costs about $0.04, or $40 per 1,000 miles. A gas car that gets 30 MPG with gas at $3.50 a gallon costs about $0.12 per mile. Public DC fast charging often costs two to three times as much as home charging, so enter the rate you actually pay.

Why your Wh/mi changes from trip to trip

  • Speed: aerodynamic drag rises quickly above 65 mph, so highway trips use more energy than city driving.
  • Temperature: heating the cabin and battery in freezing weather can cut range by 20–30%.
  • Wheels and tires: larger wheels and winter tires usually add rolling resistance.
  • Elevation and payload: climbing hills or towing increases consumption, although regenerative braking recovers some energy on the way down.

Frequently Asked Questions

How do I convert Wh/mi to Wh/km?

Divide Wh/mi by 1.609. For example, 250 Wh/mi is about 155 Wh/km. To go from Wh/km to Wh/mi, multiply by 1.609.

How do I convert Wh/mi to MPGe?

Divide 33,705 by your Wh/mi. The EPA treats 33.705 kWh as equal to the energy in one gallon of gasoline, so 250 Wh/mi works out to about 135 MPGe.

Is a lower or higher Wh/mi better?

Lower is better. Wh/mi and Wh/km measure energy used per distance, so a smaller number means the car goes farther on each kWh. For mi/kWh and MPGe, a higher number is better.

What is a good kWh/100km?

Anything from about 13 to 16 kWh/100km is excellent for a compact EV in mixed driving. Efficient sedans can stay under 13, while large SUVs and pickups often use 19 kWh/100km or more.

How is the estimated range calculated?

The tool divides your battery capacity by your efficiency. A 60 kWh battery at 250 Wh/mi gives about 240 miles. Usable capacity is usually a little lower than the advertised size, and range drops in cold weather.

Is it really cheaper to drive an EV than a gas car?

In most of the US and Europe, charging at home costs much less per mile than gasoline. Enter your own electricity and gas prices to compare. If you mainly use fast chargers, the savings can shrink considerably.

Does the calculator store my data?

No. Every calculation runs in your browser, and nothing you enter is sent to a server.