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Choose devices
Start with common essentials like a refrigerator, router, TV, fan or microwave, or add your own device with the watts from its label.
Power outage planning · United States
Will your power station keep the essentials running?
Pick your devices and your battery size. Get a clear estimate of total load, runtime in hours, and whether startup surges will overload your station – before the lights go out.
Free · No sign-up · Runs entirely in your browser
How it works
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Enter your station
Use a generic size class or type in your station’s capacity (Wh), continuous output (W) and surge output (W).
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Read the estimate
See average load, energy per day, estimated runtime, and clear warnings if running or startup power is too high.
Three numbers that matter during an outage
Capacity (Wh) – how long
Watt-hours describe how much energy the battery stores. A device that draws 100 watts for one hour uses 100 Wh. Not all of the rated capacity reaches your devices, because the battery keeps a reserve and the inverter loses some energy converting DC to AC.
Continuous output (W) – how much at once
This is the maximum power the station can supply steadily. If the devices running together draw more than this, the station will usually shut off its outlets to protect itself.
Surge output (W) – getting motors started
Refrigerators, freezers and other motor-driven devices briefly draw much more power when they start. A station needs enough surge capacity to cover that moment, or the device may never start.
Estimates, not guarantees
The appliance values on this site are rounded, illustrative estimates – they are not lab measurements and are not taken from any manufacturer. Your refrigerator might use half or twice the example value. For the most reliable result, read the label on each device or measure it with a plug-in power meter, then enter your numbers in the calculator.