Generator Wattage Calculator

Depending on the you use the generator, there are various categories to meet your needs. The most common ones are the recreation, home standby and construction generators.

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If you want a generator for home standby to run your refrigerator, you’ll need at least 2500 watts of power and if you want to use a transfer switch so that power can go directly into your home, then get a generator that can generate at least 3000 watts of power.

You should also consider the maximum and rated power of the generator. This is important depending on the items you will be running off of your generator. Items like toaster, lamps, and coffee makers are resistive, and their total load can be calculated at amps * 1. Other items like saws and drills are reactive loads. Their running load may be small, but the starting load should be calculated at running amps * 3. After the intial start less power is required for their actual operation.

Remember, simple power management will allow a smaller generator to do a big job. It happens very rarely that are all tools or appliances are operated simultaneously. So, while calculating power requirements, consider the starting requirements are only for the initial start and then additional tools may be operated in addition.

Remember Ohm’s Law from High School Physics?

Watts = Volts * Amps
Amps = Watts/Volts

So if you have two of the numbers (e.g. volts, amps) then you can find out the other (e.g. watts). This can help you to determine the rated power that you’ll need from your generator.