What is a kW to kWh calculator?
A kW to kWh calculator turns a power level and a duration into the total energy consumed. Kilowatts (kW) describe how fast electrical energy is used at any moment, while a kilowatt-hour (kWh) measures how much energy is used over a stretch of time. Because energy bills are charged per kilowatt-hour, knowing the kWh figure tells you exactly how much energy a device draws while it runs.
How does it work?
Energy in kilowatt-hours equals the power in kilowatts multiplied by the running time in hours:
Here is the constant power draw, is the time in hours, and the product is the energy in kilowatt-hours. Multiplying a rate (kW) by a duration (h) gives a total (kWh), the same way speed multiplied by time gives distance.
How to use
- Enter the power in kilowatts. If a device is rated in watts, divide by 1000 first.
- Enter the running time in hours.
- Read the energy in kilowatt-hours. The result updates automatically once both fields are filled.
Worked examples
A 2 kW load that runs for 3 hours uses:
A smaller 0.5 kW device left on for 10 hours uses:
Practical notes
To estimate cost, multiply the kWh result by your electricity price per kilowatt-hour. If your appliance is rated in watts rather than kilowatts, convert it first: 1 kW equals 1000 W, so a 1500 W heater is 1.5 kW. You can move in the opposite direction with the kWh to watts calculator, or start from a wattage and a duration using the watts to kWh calculator.
FAQ
What is the difference between kW and kWh? A kilowatt is a rate of energy use at one instant, while a kilowatt-hour is the total amount of energy used over time. A 2 kW heater running for one hour uses 2 kWh.
How do I convert watts to kilowatts first? Divide the wattage by 1000. A 750 W appliance is 0.75 kW, which you can then multiply by the running time in hours.