To determine your basic home power needs, start with these three questions:
Do you use city or well water?
Well pumps require a larger 240 volt generator (3800 watts or above).
Is your heating system electric, heat pump, or gas or oil forced air?
Gas or oil forced air systems can get by with a very small generator – as little as 2500 watts. The power needed is based on the size of the furnace fan motor. See below for details.
Electric furnaces and heat pumps typically need 15,000 watts or more to run and cannot be powered by a portable generator.
Is your hot water heater electric, gas, or oil fired?
Gas or oil fired heaters use less power – as little as 2500 watts.
Electric heaters often require at least 4500 watts.
Homeowners can often power most household appliances using between 3000 and 6500 watts.
If your home has a smaller furnace and city water, you can generally expect that 3000-5000 watts will cover your needs. If you have a larger furnace and/or a well pump, you will likely need a 5000 to 6500 watt generator.
The primary factor you need to consider is the size of your AC unit(s).
Campers, Tailgaters, and Boaters:
Industrial power needs range widely, based on what kind of tools you are using.
Keep in mind that wattage required for starting a tool or appliance with a motor will be much higher than the watts required to run the device.