kWh stands for kilowatt-hour. It is the standard unit used to measure energy, and in the EV world you will see it used in three main ways: the size of a battery pack, the efficiency of a vehicle, and the cost of electricity.
What Does a Kilowatt-Hour Actually Mean?
A kilowatt-hour is the amount of energy used when something consuming one kilowatt of power runs for one hour. A kilowatt is 1,000 watts, so a 1,000-watt appliance running for one hour uses exactly 1 kWh of electricity. You are already paying for kWh without thinking about it. Your home electricity bill is measured in kWh, typically at a rate somewhere between $0.10 and $0.30 per kWh depending on where you live.
kWh and Battery Pack Size
When you see a vehicle listed with a 75 kWh battery or a 100 kWh battery, that number tells you the total energy storage capacity of the pack. A larger number generally means more range, in the same way a larger fuel tank holds more gas. For reference, most EVs on sale today have battery packs ranging from around 40 kWh on smaller, shorter-range models up to 100 kWh or more on longer-range trucks and SUVs.
kWh and Efficiency
EV efficiency is often expressed as miles per kWh, similar to miles per gallon in a gas car. A vehicle rated at 4 miles per kWh is more efficient than one rated at 3 miles per kWh — it travels further on the same amount of stored energy. The EPA also uses a related figure, MPGe (miles per gallon equivalent), which converts kWh consumption into a familiar miles-per-gallon number for easier comparison with gas vehicles.
kWh and Charging
When you charge your EV at home or at a public charger, you are adding kWh to the battery. A Level 2 home charger might deliver 7 to 11 kWh per hour. A DC fast charger can deliver 50 to 350 kWh per hour depending on the station and the vehicle’s maximum charge rate. If your car has a 60 kWh battery and you arrive home at 20% charge, you need to add roughly 48 kWh to fill it to 100%.
The Bottom Line
kWh is simply the unit that measures how much electrical energy is stored or used. Once you understand it as the EV equivalent of gallons — for both tank size and fuel cost — the rest of the numbers you encounter when researching and owning an EV start to make a lot more sense.