Units of Measure: Gasoline vs Electric Vehicles (EV)

Energy units of gasoline and other internal combustion engines are closely related if not identical most of the time. Electric vehicles (EV) brought a new world of units. And I admit, at first it’s confusing. Today’s article is about energy units: gasoline vs electric vehicles.

Imagine this… growing up in an era where you couldn’t charge your phone. No USB-C, no Micro USB, no Lightning Port… don’t worry, it was all unnecessary.

Before you close this page let me tell you… that’s because at that time your rotary dial phone would only work at your house. It wasn’t a mobile phone, it was plugged in. Even changing its place at home could be a challenge.

Gasoline Energy Units

With internal combustion engines, including gasoline, for decades things didn’t change much.

The tank needle kept on getting lower until it got close to empty… and you brought it back up after a few minutes at your usual fuel pump.

When you’re having a drink with your friends you’re talking about horsepower.

And, let’s face it, in the last few years, fuel economy became more and more relevant. There you go talking about liters per 100 kms, miles per gallon, or kms per liter, depending on your location.

At the same time, when you fill up your tank you’ll consider liters or gallons.

With EVs, it’s a whole new ballgame. I mean… in cars.

FREE BONUS: Check out our Infographic on Units of Measure (Gasoline vs EV). Click here and follow the instructions.

Electric Vehicles Units

You saw this coming: then electric vehicles started to gain strong traction on the market.

After many years of being almost an urban legend, in a few years, EVs changed a lot; they went from urban cars that you couldn’t drive out of town without running out of battery to cars that can go on long trips.

And a whole world of doubts came with it, and some are still very present.

Let’s take the first one; which, I admit, I had for a while. Have you noticed that anything and everything on electric cars is measured in kilowatts (kW)? Or kilowatt-hour (kWh)? Or both?

Yes, I remember the days when I couldn’t distinguish kW and kWh.

Maybe you’re in that situation. Maybe you just found out that they actually mean different things.

Sometimes I would mention one but if you were a little bit more informed than me, you’d know I was talking about the other.

Energy Units: Gasoline vs Electric Vehicles

Let’s now go over 4 of the most common types of units for each of these vehicles as you can see in this infographic.


  • Gasoline: Horsepower
  • EV: kW (kilowatt)

One of the first characteristics that you’d check about a car in the past was the power. Horsepower was the most used unit. But you could also use kW.

Horsepower was more usual when talking to your friends, participating in web forums, and many other places.

Here in Portugal the car’s official documentation actually indicates power in kW.

And if you want to change from one to your favorite, that’s easy:

  • 1 horsepower = 0.745699872 kilowatts

If you prefer it the other way around:

  • 1 kilowatt = 1.34102209 horsepower

In this case, I mentioned two units but they actually mean the same. And you can easily convert from one to the other.

It’s your personal preference. I’m more used to horsepower but I admit I notice that the usage of kW is getting less rare.

Tank and Battery capacities

As you would expect, with EVs there’s no filling up to be measured in liters or gallons.

The amount of energy you recharge into the battery is measured in kWh.

Do you know what’s also measured in kWh? Hint: take a look at your electricity bill.

Let’s imagine your EV is charging at home at… 2,3 kW.

Using 2,3 kW for 2 hours means you’ve used… 4,6 kWh (=kW * number of hours= 2,3 * 2 ).

If you want to use less kWh, you have three choices:

  1. Reduce the power usage (less kW for the same time = less kWh);
  2. Reduce the time your using that power (same kW for less time = less kWh);
  3. Reduce both of them.

FREE BONUS: Check out our Infographic on Units of Measure (Gasoline vs EV). Click here and follow the instructions.


Recharge Rate

  • Gasoline: Not Applicable
  • EV: kW (kilowatt)

We could easily use some measures like liters or gallons per minute and that might be important in some professional areas. But when you took your gasoline car to the fuel pump you never measure that. You just fill it up and that’s it.

You also didn’t think about it before buying your gasoline car.

It’s a different story when it comes to Electric Vehicles.

You’re much better off with a car that can charge at 50kW than one that only gets 20kW.

And even better if it gets 150kW. And so on…

But the more your charging speed grows, the less important each speed increment is.

50kW over 40kW is a significant improvement. 260kW over 250kW isn’t relevant for most people.

Bear in mind that when a car advertises charging power, they mention the peak power.

EVs tend to charge at peak speeds when their battery SoC is somewhere between 10%-20% and slowly drops. That allows you to get to 50%-70% relatively fast but take a lot longer afterward to get to the full 100%.

The industry standard to measure fast charging time focus on going from 10% to 80%, which is what you should do on long trips.

Fuel Economy and Energy Efficiency

  • Gasoline: Liters per 100 km, Miles per gallon and Kms per liter
  • EV (km): Wh/km (watt-hour per km) and kWh/100 kms (kilowatt-hour per 100 km)

With all the different units until now, measuring efficiency also had to be different.

There are two main options when using km: efficiency per km (Wh/km) or per 100 km (kWh/100 km).

And it’s easy to change between them.

145 Wh/km is the same as 14,5 kWh/100 km.

FREE BONUS: Check out our Infographic on Units of Measure (Gasoline vs EV). Click here and follow the instructions.

If you are not sure what that implies in range, let’s imagine a simple example.

Let’s say your car has 55 kWh.

If you divide 55 (kWh) by 14,5 (kWh/100 km) times 100… (55 / 14,5) * 100 = 379 kms

Conclusion on Units of Measure: Gasoline vs Electric Vehicles

For years we’ve seen the gasoline car as the standard fuel for cars with its implication on the units for fuel amount, tank capacity, and average consumption

Electric vehicles use other units and I reckon that it can be a bit confusing to begin with.

I hope this article made everything clearer and don’t forget to click the link and have access to the infographic.