Enter an energy total in kWh and a number of hours to find the average power in watts over that period.
How to Use the Kilowatt-Hours to Watts Calculator
Enter an energy total in kWh and the number of hours it was measured over. The average power comes back in watts, which suits small devices better than a kilowatt figure would.
Finding a Rough Idle Draw
Smart-meter apps and plug-in energy monitors often report a device's usage in kWh over a day rather than an instantaneous wattage, which makes this a handy way to back into a rough standby or idle draw. A device that used 0.5 kWh over 24 hours of being left plugged in — a router, a game console in rest mode, a TV that's never fully off — works out to just over 20 W average.
Average Power (W) = (Energy (kWh) × 1,000) ÷ Time (hours)That figure is only as good as the assumption that the draw was roughly constant across the period. A device that idles quietly most of the day and then runs a short, power-hungry task will report the same kWh total as one that draws steadily throughout — the average can't distinguish between the two, only the total energy behind them.