How to Size a Home Gas-Powered Generator

Gas generators work by converting gas power in to electricity. Getting the right size generator is important when that power outage happens. You don't want a generator that is too small, or you'll be out of power anyway; if it's too large, you'll be wasting electricity and money. In order to size a generator, you will need to determine how many kilowatts you'll be using when running it. Since generators are sized in kilowatt output, once you have that, it's easy to find the right one.

• 1

  Decide what devices you want to run while using the generator. For example, if you plan to use the generator for emergency situations, you may only plan to use the lights, water heater and basic electronics.

• 2

  Find the number of watts each device requires to run. This can usually be found on the product's name plate or in the owner's manual. Some devices may list amperage and voltage instead of watts. You can use amps and volts to determine wattage using the following formula: Volts x Amps = Watts.

  For example, if you are calculating wattage for a device that uses 2.2 amps and 120 volts, it would need 264 watts.

• 3

  Add the wattage for every device you plan to run on a generator together.

• 4

  Convert watts to kilowatts(kW), rounding up to the nearest whole kilowatt. 1,000 watts is equal to 1 kilowatt, so if your total wattage equals 10,500 watts, you would use 11 kW. Gas Generators are sized according to kilowatt output, so your kilowatt usage is the size of generator you need.