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Home Standby Generator Sizing Guide

The generator size required depends on what you intend to power during an outage, rather than the size of your home.

While a straightforward approach is to match the generator size with the maximum power supplied by the utility company, it's important to note that you may not be utilizing all that power unless you're consistently tripping circuit breakers. As a result, many opt for a slightly smaller generator that can fulfill their specific power needs. Consider whether you plan to run multiple appliances simultaneously or if you're comfortable taking turns using high-power devices like ovens and dryers.

For a rough estimate of what your generator can power, refer to the chart below.


 Size Application Suitable For
6 kW - 8 kW Necessities

• Most homes don't use more than 5 kW / hr on average. 

• Power your fridge, freezer, water pumps, fans, microwave, kettle, a single stove element, coffee maker, and all your lights. 

• Very common for cabins, cottages, off-grid homes and basic necessities for day to day living

• Superior to portable generators. 

10 kW Necessities Plus

• Powerful enough for window type air conditioners but not for large central air.

• Commonly used in homes that don't need to use central air conditioners, but you can easily power a few window air conditioners

12 kW - 13 kW Suitable For Most Homes

• Enough power for most homes.

• Using all your heavy appliances at the same time may not be possible. 

20-22 kW

Whole Home

 • You have enough power and the ability to carry on as if an outage never happened.

• In extreme conditions, it might not be enough for the oven, stove and central air plus dryer all at the same time.

25 kW

Large Home

• Better solution for homes with large or multiple central air conditioning or homes that rely on electric heat.

30 kW

Large Home 

Two-Family Home

 • Typical 400 Amp Homes 


Check out this home standby sizing calculator for more accurate calculations.