Figures are typical values from manufacturer labels and industry sizing charts. Your appliance may differ, so check its label for the exact number.
Running vs. starting watts
Anything with an electric motor or compressor (fridges, freezers, pumps, air conditioners, washers and power tools) needs a short burst of extra power to get moving. That burst is the starting watts figure. Resistive appliances like heaters, kettles, toasters and lights have no meaningful surge. They draw the same power from the moment you switch them on.
When sizing backup power, add up the running watts of everything you'll use at the same time, then add the single largest "starting minus running" difference. Our calculators do this automatically.
Watts, amps and volts
Standard U.S. outlets supply 120 volts. To convert, use watts = amps × volts. A device rated at 5 amps uses about 600 watts. Large appliances such as electric dryers, ranges and some well pumps run on 240 V circuits and can only be powered by generators or home batteries with a 240 V output.