Backup Generator Sizing Calculator

Getting the right-sized standby generator for your home is the single most important step before buying which is why we created this simple online calculator. One size doesn't always fit all, so be sure to size your new generator based on the following criteria:

1. The Size of Your Home
2. The Size of Your Air Conditioner
3. How Much You Want to Power

Use the following generator size calculator to figure out what size generator you need.

Step 1: Home Details - What is the Size of your Home?

Select Square Footage Under 1,000 sq. ft. 1,000 - 1,600 sq. ft. 1,600 - 3,000 sq. ft. 3,000 - 5,000 sq. ft. 5,000+ sq. ft. Zip Code

Step 2: Central Air Conditioner Size

AC units come in several sizes depending on their BTUs or Tons. Since central air conditioners typically use more wattage than any other appliance in your home, you will want to make sure you get a generator that can handle the load.

Select Central Air Unit 1 Not Applicable 2 Tons 3 Tons 4 Tons 5 Tons Select Central Air Unit 2 Not Applicable 2 Tons 3 Tons 4 Tons 5 Tons

Step 3: What Do You Want To Power?

Choose what your power needs are clicking below. Select whole house if you want everything to run at the same time during a power outage or customize to.

Whole House

Customize

Whole House

Selecting whole house provides a backup generator recommendation based on your home's size and corresponding outlets and lighting requirements and assumes natural gas appliances in the baseline calculation. If your home has electric appliances like an electric range, electric clothes dryer, electric water heater, etc., you can add these items below to accurately reflect your home's specific backup power needs.

Customize

Use this option if you want an emergency back-up generator without powering your entire home. Be sure to select each electrical appliance you wish to have backup power for in your home below.

Essentials

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1

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Central AC

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1

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AC Tonnage 1

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1

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AC Tonnage 2

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0

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Window AC

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0

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Well Pump

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0

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Electric Water Heater

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0

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Gas Water Heater

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0

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Gas Furnace

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1

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Refrigerator

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1

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Freezer

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0

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Sump Pump

Appliances

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0

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Electric Oven/Stove

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0

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Gas Oven/Stove

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1

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Microwave

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1

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Dishwasher

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1

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Garage Door

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0

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Electric Dryer

Extras

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0

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Computer

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0

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Wi-Fi

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0

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Hot Tub

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0

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Sauna

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0

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Pool

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0

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Security

Lightings and Outlets

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Master Bedroom

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Bedroom

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Office

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Living Room

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Dining Room

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Family Room

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Kitchen

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Kitchen Outlets

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Hall/Stairs

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Bathroom

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Basement

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0

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Laundry Lights

Appliances

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0

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Refrigerator

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Electric Dryer

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0

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Electric Oven/Stove

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Electric Cooktop

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0

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Garbage Disposal

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0

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Freezer

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0

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Electric Water Heater

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0

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Garage Door

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0

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Microwave

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0

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Dishwasher

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0

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Washer w/Gas Dryer

Extras

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0

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Gas Furnace

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0

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Boiler

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0

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Window AC

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0

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Heat Pump

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0

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Sump Pump

Don't see an item you need? Add Your Own

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Item Name Wattage

Add Item

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* PED Sizing Tool assumes that you will use load management and not run all appliances at the same time.
We recommend having an licensed electrician verify your specific electrical requirements before purchasing.

Learn More about Home Standby Generators

Installation Expectations

How To Pick The Perfect Standby Generator

This sizing tool is intended for estimating purposes only. This tool assumes that you will use load management and will not run all appliances at the same time. Transfer switches should be sized to your particular application. We recommend having an licensed electrician or certified installer verify your specific electrical requirements before purchasing. All installations must be performed by a certified electrician in accordance with local codes to maintain manufacturer warranties. Call Our Experts: 800-800-3317

Standby Generator Options

Your Selections

This sizing tool is intended for estimating purposes only. This tool assumes that you will use load management and will not run all appliances at the same time. Transfer switches should be sized to your particular application. We recommend having an licensed electrician or certified installer verify your specific electrical requirements before purchasing. All installations must be performed by a certified electrician in accordance with local codes to maintain manufacturer warranties. Expert Recommends Articles Installation Expectations How To Pick Perfect Standby Generator Call Our Expert: 800-800-3317 * PED Sizing Tool assumes that you will use load management and not run all appliances at the same time Contact Us| Update Preferences|

When you click on "View All Results," you'll see all the standby generator models that will meet your home's power needs in kilowatts (1 kilowatt= 1,000 watts).

You should never use more than 80% of your standby generator's maximum power output to prevent strain on the unit, so oversizing by roughly 20% is generally recommended.

Air conditioners are extremely important to consider because they use significant amounts of electricity, requiring about 3.517 kilowatts of power for each ton of capacity. If your generator is too small, it will either not be able to handle an air conditioner, or it'll handle an air conditioner and little else.

If you have any unique sizing questions that you don't feel our home generator sizing calculator answered, please call us at (866) 554-4328 to speak with an expert.

After finishing your backup generator sizing, you'll need to choose the right transfer switch.

By  Ken D.
Product Expert

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