Enter watts to find the same power in kilowatts, then add operating time to estimate energy use in kilowatt-hours.
Advanced options
Kilowatts measure power. Divide watts by 1,000 to get this value.
Kilowatt-hours measure energy over time. This estimate assumes the device stays at the entered power for the full operating time.
Table of contents
How to use our Watts to Kilowatts Converter
- Find the device's power rating in watts on its label, manual, product specification, inverter listing, or watt meter.
- Enter it in "Power (watts, W)." You can enter 1500, 1,500, or 1500 W.
- Leave "Operating time (hours, optional)" blank if you only need the watts-to-kilowatts conversion. Enter the number of hours the device runs if you also want an energy estimate.
- Select "Calculate." Read "Power in kilowatts" first for the direct conversion.
- If you entered time, read "Estimated energy used" in kWh. For example, 1.5 kW running for 4 hours uses 6 kWh.
- Open "Advanced options" only if you need 3 or 9 displayed decimal places instead of the default 6.
Definitions
Watt (W): A unit of power, or the rate at which a device uses or produces energy.
Kilowatt (kW): A unit of power equal to 1,000 watts. [1]
Kilowatt-hour (kWh): A unit of energy equal to using 1 kilowatt for 1 hour. [2]
Operating time: The number of hours the device runs at the entered power level.
Common mistakes and quick fixes
Mistake: Entering a utility-bill amount, such as 500 kWh, in "Power (watts, W)."
Fix: Enter the device's watt rating. kWh measures energy used over time, while watts measure power.
Mistake: Treating kW and kWh as the same unit.
Fix: Use kW for power. Enter running time to calculate kWh, which is energy used during that time.
Mistake: Typing a comma as a decimal mark, such as 1,5 for one and a half watts.
Fix: Use a decimal point for fractions: enter 1.5. Use commas only to group thousands, such as 1,500.
Mistake: Assuming the label's watt rating is the exact power used at every moment.
Fix: Use a measured or average watt value when available. The kWh estimate assumes power stays at the entered level for the full time.
Limitations & Key Assumptions / Boundary Conditions
- The watts-to-kilowatts conversion is exact: 1 kW equals 1,000 W.
- The optional kWh estimate assumes the device stays at the entered wattage for the entire operating time.
- A nameplate may show maximum, rated, or input power instead of the device's changing actual power draw.
- This calculator estimates energy only. It does not calculate electricity cost or account for utility rates, voltage, efficiency, or power factor.
Methodology
Power conversion
The calculator divides watts by 1,000 because one kilowatt equals 1,000 watts. [1]
kilowatts = watts / 1000
For example, 1,500 W divided by 1,000 equals 1.5 kW.
Optional energy estimate
If you enter operating time, the calculator multiplies power in kilowatts by hours. The result is kilowatt-hours, which measure energy used over time. [2]
energy in kWh = kilowatts x operating hours
For example, 1.5 kW used for 4 hours equals 6 kWh. Leaving operating time blank hides this estimate. Entering 0 hours gives 0 kWh.