Take the guesswork out of your generator size needs. Shop confidently with an accurate calculation.

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Calculate Your Minimum Generator Size

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 systems running. GeneratorMart generators are reliable, affordable, and designed to give you years of worry-free service.

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

Determine Power Requirements

To determine power requirements, write down your power 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
Volts and Amps given separately Volts x Amps = Watts
Kilowatts or KW Kilowatts / 1000 = Watts
Watts or Watt-Hours Watt-Hours – Watts

Add up the Total Watts and add to 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.

If you are starting from scratch and initially trying to understand the basics of residential generators, read our buying guide.

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