What Size Standby Generator Do I Need?

Standby generators will provide adequate backup power for your home, but only if they are the right size. So, what size standby generator do you need? Keep reading to find out.

How big of a generator do I need to run my whole house?

To determine the size of standby generator you’ll need, first identify which appliances and electronics you want to keep running in the event of a power outage. Then, find out the wattage requirements for each of those items. (Hint: most appliances and electronics will have a label indicating their wattage).

Add a safety buffer of 1.25 kilowatts to the kilowatts to provide for future power requirements. For your residence, this is the minimum Generator Capacity. Your house will need at least an 18-22 kilowatt generator if your generator’s minimum capacity is 17.5 kilowatts.

Running even the most vital home appliances, such as the freezer and the pump for your well, may be done with a generator that is rated between 5,000 and 7,500 watts. All of these appliances may be powered simultaneously by a 7500-watt generator.

Related Questions and Answers

How do I measure a standby generator?

This video will provide more information:

What size generator do I need for a 100 amp service?

The size generator you need will produce 8 to 12 kilowatts.


The size of the standby generator you need will depend on your home’s overall energy requirements. This includes all appliances and electronics you need to run during a power outage.

If you are trying to figure out what size generator you need, there is a simple formula that can help you. The formula is the square footage of your house divided by 1,500. That will give you the number of amps your standby generator needs.

NEXT UP: Can You Put a Standby Generator in a Barn?

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James Sylvester
About James Sylvester

James S. Sylvester is an experienced OSHA Safety Supervisor with years of experience in the construction and oil & gas industries. He focuses on workplace safety, occupational health and safety systems. Learn more about James' here or connect with him on Twitter