How to Calculate Generator Loads

Calculating a generator load requires determining the total power requirement for a home.

Calculate Your Home's Wattage

This can be done by using a manual calculation or utilizing an online generator size calculator. The proper load for a generator needs to be calculated before one is purchased. Once you have the power requirement you can then shop around and compare different kinds of units to find the one that you want to use with your home. .

Step 1

Find the wattage used by all of the electrical devices that are used in your home during the year. This can include a water heater, furnace fan, a refrigerator, coffee maker and any other electrical equipment used in the home.

Step 2

Write the wattage of each electrical device on a piece of paper.

Step 3

Add together the watts used by each electrical device by hand or use a calculator. Round the result up to the next round number to determine the generator load required for your home.

Generator Size Calculator

Step 1

Go to an online generator size calculator, such as the one provided by Kohler.

Step 2

Enter the square footage of your home in the Square Feet of Residence field.

Step 3

Put a check in the box for any electrical device that you use in your home. Options include Kitchen Appliances, Portable Kitchen Appliances, Entertainment and all other electrical devices.

Step 4

Click the “calculate power requirements” button to see the generator load or size of generator that is required for your home.

Things You Will Need

  • Pencil
  • Paper
  • Calculator


  • Rounding the wattage to the next whole number provides a cushion in case you have an additional electrical device being used in your home.


  • If you do not include all of the electrical devices you use during the year the generator may not have enough wattage to power your whole house.

About the Author

Cameron Easey has over 15 years customer service experience, with eight of those years in the insurance industry. He has earned various designations from organizations like the Insurance Institute of America and LOMA. Easey earned his Bachelor of Arts degree in political science and history from Western Michigan University.