About the kW to kWh Calculator
This calculator converts kW to kWh. kW is a thousand watts, the usual way to rate motors, heaters, air conditioners and generators, and kWh is one kilowatt of power used for one hour, the unit your electricity meter counts and your bill charges for. The tool multiplies the power by the time you enter, and it can add a price per kWh to show what the electricity costs. Enter your figures and the answer appears at once, together with a few related values, and you can copy the result with one tap. The sums are done in your browser and nothing is sent anywhere.
Updated October 2026
How to use the kW to kWh Calculator
- 1Enter the value in kW.
- 2Fill in the other boxes that the kW to kWh calculation needs, such as time, voltage or power factor.
- 3Read the answer in the large result box.
- 4Check the extra rows for related values.
- 5Press Copy result to keep it.
When you need kW to kWh
Anyone reading an electricity bill meets the problem that appliances are rated in kilowatts while the meter and the bill count kilowatt-hours. A kilowatt tells you how fast something uses energy; a kilowatt-hour tells you how much it used. To estimate the cost of running an air conditioner, an electric heater or an oven for an afternoon, you multiply the rating by the time.
Solar and battery planners use the same sum to size storage: a 3 kW load that runs for four hours needs 12 kWh. Businesses use it to compare machines, and landlords use it to split a shared heater. If the time is in minutes or days, choose that unit and the tool converts it.
How the kW to kWh sum works
kWh = kW × hours. For example, a 2.5 kW heater that runs for 8 hours uses 2.5 × 8 = 20 kWh, and at a price of 0.30 per kWh that comes to 6.00.
The displayed answer is rounded to six significant figures, but the sum itself is not rounded, so converting kW to kWh and back again gives you the number you started with.
- Hours, minutes, seconds or days
- Optional price per kWh
- Also shows watt-hours and megajoules
Mistakes to avoid when converting kW to kWh
The most common mistake is to treat kW and kWh as the same thing. Another is to forget that a device does not always run at full rating: a fridge with a 150 W motor may only run a third of the time, so use the average running time, not the full day.
On phone and computer
On a phone, type in the boxes one after another and read the kWh result underneath; the Copy button puts it on the clipboard for a message or a note. On a computer the inputs sit on the left and the answer on the right, so you can change one figure and watch the kWh value move. The kW to kWh page works the same on both. Once you have energy, Electricity Cost Calculator turns it into a bill. Watts to kWh Calculator works from smaller loads, kWh to kW Calculator goes back to power, and Power Converter changes the unit of power.
Features
- kW to kWh in one step
- Related values shown with the answer
- Clear messages for impossible inputs
- Copy the result with one tap
- Private: nothing is uploaded
- Works on phone and computer
Frequently asked questions
How do I convert kW to kWh?
kWh = kW × hours. For example, a 2.5 kW heater that runs for 8 hours uses 2.5 × 8 = 20 kWh, and at a price of 0.30 per kWh that comes to 6.00.
What is the formula for kW to kWh?
kWh = kW × hours. The calculator applies it exactly and rounds only the displayed answer.
What is the difference between kW and kWh?
kW is a thousand watts, the usual way to rate motors, heaters, air conditioners and generators. kWh is one kilowatt of power used for one hour, the unit your electricity meter counts and your bill charges for. They measure different things, which is why converting from kW to kWh needs more than a simple multiplication in some cases.
Does the kW to kWh calculator work out the cost?
Yes. Type the price you pay per kWh in the optional box and the cost of the energy is added to the result. Leave it empty if you only need the energy.
How many kWh does 1 kW use in a day?
A device that draws 1 kW for 24 hours uses 24 kWh. At half the time it uses half the energy.
Is this kW to kWh calculator free and private?
Yes. It is free, needs no account, and runs in your browser, so the figures you type are not uploaded or stored. It is meant for planning and learning; for wiring or safety work, check the result against your equipment's rating plate and local rules.