Adding up the running watts and the highest starting wattage of all the devices you wish to power with a generator will help ...

To determine whole-house generator sizing, the first step is for the homeowner to determine the number of appliances and electrical devices that will be run and calculate the total wattage.

Find the right generator size and calculate the power you need to keep your home running smoothly.

Your generator also must have at least a 30-amp/240-volt output. To calculate wattage for a standby generator, check a year's worth of electric bills to find the highest kilowatt usage.