Miles Per kWh Calculator
- Miles Per kWh
- MPGe
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You'll often hear owners of electric vehicles (EVs) refer to the term miles per kWh (mi/kWh) when discussing their vehicle's energy efficiency, but what does it actually mean? While the fuel efficiency of petrol vehicles is commonly measured in miles per gallon (MPG), we obviously need a different unit of measurement for EVs. That's where miles per kWh comes in.
What is miles per kWh?
The miles per kWh measurement shows how many miles an EV can travel using one kilowatt-hour (kWh) of electricity. When assessing an EV's running costs, looking at the mi/kWh can help you compare its energy efficiency to other electric vehicles (and, with a little math, to gas vehicles too).
On average, most EVs achieve around 3 to 4 miles per kWh. However, less efficient models may only get around 2.5 miles per kWh, while high-efficiency models can reach up to 5 miles per kWh or more. 1
How is miles per kWh calculated?
The process for calculating miles per kWh is fairly straightforward - you divide the miles driven by the electricity used (in kWh). I'll give a simple example. If your EV covers 50 miles using 10 kWh, it achieves 5 miles per kWh (50 divided by 10).
Why is miles per kWh important?
There are several reasons why mi/kWh can be an important metric:
- Efficiency insight: It measures an EV's energy use directly.
- Cost Savings: Higher miles per kWh can mean lower electricity costs (depending on the cost of electricity at time of charge).
- Environmental Impact: Greater efficiency typically means less energy being used and, therefore, fewer emissions.
For more detailed information on EV efficiency and energy use, you may wish to check out the DOE Alternative Fuels Data Center.
You'll obviously find EV efficiency data on manufacturer websites and from comparison reviews on websites such as Inside EVs (USA) and EV database (UK). But, it's worth mentioning the elements that will directly affect the real-world efficiency you get from your EV. So, let's take a look at those:
Factors affecting miles per kWh
As with the MPG efficiency of petrol and diesel vehicles, there are factors that directly affect the energy efficiency you get from your EV. These include:
- Driving Habits: Speeding and rapid acceleration will reduce your efficiency.
- Terrain: Driving up hills requires more energy. If you're driving uphill, the electric motor has to work harder to overcome gravity, which increases its energy consumption and reduces your car's range.
- Temperature: Extreme heat or cold can significantly affect your battery's performance. Studies suggest EVs lose 2%-5% of range in hot weather below 90°F, but up to 20%-30% at higher temperatures. And, research has shown that in winter, chemical reactions in the battery slow down and more energy is used for heating. This leads to a greater range loss compared to summer. 234
- Accessory Use: Using air conditioning, heating, and other accessories will increase the energy drain of your EV's battery. 5
So, we've learned that adjusting your driving habits can help you maximize your EV's efficiency and increase the range. MYEV has an article with ten tips for maximizing your EV's range, which you can find here.
Other frequently asked questions
Here are some answers to other questions about miles per kWh:
How does miles per kWh relate to my electricity bill?
The miles per kWh figure provides a snapshot of your EV's efficiency. To then estimate the overall electricity cost for running your vehicle, simply multiply the kWh used by your electricity cost per kWh.
Is a higher miles per kWh always better?
Generally, yes. A higher miles per kWh figure means your EV uses less electricity to travel the same distance, which would potentially lower your energy bill. However, there are obviously additional factors to consider when deciding which EV to buy. Things like the purchase cost of the vehicle, insurance, and maintenance.
How does miles per kWh compare to MPGe?
While miles per kWh measures distance per kilowatt-hour, MPGe translates this to a gasoline equivalent (we have a MPGe calculator here, by the way). Both metrics are useful but offer different perspectives on efficiency.
Summary
I hope this article has helped you understand a little more about the miles per kWh measurement, and the factors that affect how many miles of range you might get from your battery. It’s worth remembering that ongoing research and technological advances will continue to influence these metrics. So, as battery technology improves, the efficiency of EVs should also increase.
Should you have any feedback, suggestions or questions about this calculator and article, please get in touch.
Calculator created by Alastair Hazell.References
- Inside EVs. U.S. Electric Cars Listed From Lowest To Highest Energy Consumption
- Recurrent. Winter & Cold Weather EV Range
- Recurrent. Study: Summer & Hot Weather on Electric Car Range
- AAA. Study: What’s the Real Range of Electric Vehicles?
- Perrys (UK). What Reduces the Range on Your Electric Vehicle?