Sizing Calculator

Determining the right size home standby generator (HSB) for your home is the first step in protecting your family from power outages but it can also be intimidating. Both generators and the appliances in your home use watts (or kilowatts for 1,000 watts) to denote how much electricity they make or use.The below calculator is designed to add up the electrical appliances in your home to figure out what size natural gas or propane generator will be right for you. If you are starting from scratch and initially trying to understand the basics on residential generators, visit our education articles on generator basics, installation guide, or sizing guide.

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Additional Sizing Factors to Consider

Sizing your standby generator correctly is critical because it ensures that all of your necessary appliances will work properly during an emergency.

Identify Your Power Needs

If your electricity goes out, generators provide power to keep your essential household electrical items running. GeneratorMart generators are reliable, affordable, and designed to give you years of worry-free service.

Choose a generator with enough power to keep your essential circuits in your home, plus a few conveniences. The easiest way is to add up the wattage of all the essential circuits, add 20%, then choose a generator that meets or exceeds that number.

Determine Power Requirements

To determine power requirements, write down your requirements in watts found on your devices. You can use the below table to help identify the number of watts your generator will need.

Label Stats

Find Watts

Volt-Amps or VA

Volt-Amps = Watts

Volt and Amps given separately

Volt x Amps = Watts

Kilowatts or KW

Kilowatts / 1000 = Watts

Watts or Watt-Hours

Watt-Hours — Watts

Add up the total watts and add your calculator results to determine how much power your home is likely to leverage during an outage. Divide the total watts by 1000 to find kilowatts and add a 20% safety margin. This final number is your minimum Generator Capacity requirement for your home.

Avoid going with the bare minimum generator as home power requirements increase over time.

Choosing the Right Standby Generator

Once you calculate your power needs and requirements, you are ready to move forward by selecting other important factors unique and relevant to your home. Homeowners should carefully consider that if you have too small a unit, home appliances may not operate, and a too-large unit is wasteful and inefficient

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