Calculator About

What's enough for you?

Tick what you'd plug in during an outage. Every figure below is a typical published value — check your own labels for the final word.

Your devices

Refrigerator (standard, 18-22 cu ft)150W · surge 800WChest freezer120W · surge 700WRouter and modem15WLaptop60WPhone charging15WLED lights, four bulbs40WTV, 55 inch LED110W · surge 150WBox fan75W · surge 200WSump pump, 1/3 hp900W · surge 2200WWell pump, 1/2 hp1000W · surge 3000WMicrowave, 1000W output1400W · surge 1600WCoffee maker1000WSpace heater, high1500WElectric blanket80WGas furnace blower600W · surge 1800W

Your load

Average draw0 W

Worst-case continuous0 W

Peak surge to start0 W

Runtime = capacity × 0.95 usable × 0.87 inverter efficiency ÷ average draw. Surge rule: station output × 1.5 must clear your biggest spike while everything else keeps running. Conservative on purpose.

Watts Enough? — the math before you buy backup power.

Estimates are deliberately conservative and based on typical published device figures; your appliances may differ. Nothing here is medical, electrical-safety or financial advice. How the numbers work & full disclosure.