kW to kWh Calculator

Enter a power in kilowatts and a number of hours to calculate the total energy used in kilowatt-hours.

How to Use the kW to kWh Calculator

Enter the power draw in kilowatts and the number of hours it runs; the energy total in kWh recalculates on every keystroke.

Kilowatts and kilowatt-hours get mixed up constantly, but the relationship is the same one that connects speed and distance. A kilowatt is a rate — how fast energy is flowing at a given moment, the electrical equivalent of speed in miles per hour. A kilowatt-hour is a total — how much energy actually moved over some stretch of time, the equivalent of the miles you've actually driven. A car doing 60 mph for two hours covers 120 miles; a heater drawing 2 kW for five hours uses 10 kWh.

Energy (kWh) = Power (kW) × Time (hours)

Utility bills are always denominated in kWh, because that's the quantity that was actually consumed and has to be paid for — a device's kW rating alone says nothing about the bill until a duration is attached to it. This calculator does that multiplication for one device over one stretch of time; for a whole household's worth of appliances at once, the site's Electricity Bill Calculator runs the same math across a list.