kW vs kWh: Power and Energy for EV Charging in Indonesia

Two units come up constantly with electric vehicles (battery electric vehicles / BEVs): kW and kWh. They look almost the same but mean different things, and mixing them up makes charging confusing. This guide explains the difference in plain terms and shows how each one shapes what you pay and how long you wait in Indonesia.

By mht-dev, Frontend Engineer & Creator

A frontend engineer who bought a first electric car in March 2026 and built EV Charge Calculator while working out the real cost of charging it, writing every guide from an everyday new EV owner's perspective.

Power vs energy

kW (kilowatt) is power: the rate at which energy flows, in other words how fast. kWh (kilowatt-hour) is energy: the amount delivered or stored. A simple way to picture it: kW is how fast water flows from a tap, and kWh is how much water ends up in the bucket. A charger rated at 50 kW that runs for one hour delivers 50 kWh; the same charger in half an hour delivers 25 kWh.

For an EV, your battery's capacity is measured in kWh (say, 60 kWh), the charger's speed is measured in kW (say, 7 kW at home or 100 kW on DC), and charging time is simply the energy you need divided by the power: kWh ÷ kW = hours. So adding 30 kWh on a 7 kW home charger takes about four hours, while the same 30 kWh on a 100 kW DC charger takes well under half an hour.

On your bill and in this calculator

Your electricity is billed per kWh (energy), so the cost of a charge is the energy you add (kWh) times your rate per kWh. Power (kW) decides how long it takes, not the price: a faster charger fills the same kWh sooner but the energy cost is the same (public DC chargers do often charge a higher rate per kWh, but that is a pricing choice, not a property of kW). That is exactly how the charging cost calculator works: it takes your battery size in kWh, the charge percentage, and the charger power in kW, then shows the energy, the time, and the cost using your local rate per kWh.

Frequently asked questions

What is the difference between kW and kWh?

kW (kilowatt) is power: how fast energy flows. kWh (kilowatt-hour) is energy: how much is delivered or stored. A 50 kW charger running for one hour delivers 50 kWh. Your battery capacity and your electricity bill are in kWh; charger and car charging speeds are in kW.

Why is my electricity bill measured in kWh?

Because you pay for energy used, not the rate it was delivered at. A kWh is a fixed amount of energy, so billing per kWh is fair regardless of how fast you used it. Charging an EV adds kWh to the battery, and you pay your rate per kWh for each one. That is the basis of the charging cost calculator.

How do kW and kWh affect charging time?

Charging time is the energy you need (kWh) divided by the charging power (kW). For example, 30 kWh at 7 kW takes about 4 hours; the same 30 kWh at 100 kW takes well under half an hour. More kW means less time for the same kWh, but the energy cost stays the same.