Home Backup Generator Sizing Calculator

Select the appliances you need to run during a power outage to calculate your exact running wattage and starting surge requirements.

Kitchen & Essentials

Water & Critical Systems

Comfort & Electronics

Total Running Watts 0 W
Highest Starting Surge 0 W
Min. Generator Required 0 W

Need a Transfer Switch Installed?

Plugging a generator directly into your breaker panel ("backfeeding") is illegal and deadly to linemen. Connect with licensed electricians to install a safe, code-compliant manual transfer switch or interlock kit.

Recommended Generators Based on Your Load

Standard sizing dictates your generator must be able to handle the Total Running Watts plus the Highest Single Surge Wattage of your appliances.

Essentials Only (0 - 3,000W)
Portable Power Station / Inverter
Quiet, safe for indoors, and perfect for keeping the fridge cold, phones charged, and internet running.
Shop EcoFlow Solar Generators
Standard Backup (3,000W - 8,000W)
Portable Gas/Dual-Fuel Generator
The sweet spot for home backup. Powers the well pump, fridge, microwave, and a window AC unit without breaking the bank.
Shop Portable Generators on Amazon
Whole Home (8,000W+)
Heavy Duty / Standby Generator
Required if you intend to run Central AC, electric water heaters, or massive electric well pumps simultaneously.
Shop Large Generators on Amazon

Understanding Running Watts vs. Starting Watts

The "Surge" Motor Factor

Any appliance with an electric motor (refrigerators, well pumps, AC compressors, furnace blowers) requires a massive burst of power for a split second to overcome inertia when turning on. This is called the Starting Wattage or Surge Wattage. A refrigerator that runs continuously at 700 watts may need up to 2,200 watts just to click on.

How the Math Works

You do not need to add the surge wattage of every appliance together, because you will not start them all at the exact same millisecond. To properly size a generator:

  1. Add up the Running Watts of every appliance you want to run at the same time.
  2. Find the appliance with the Highest Starting Wattage.
  3. Add that single highest surge number to your running watts total.

Frequently Asked Questions

Can I use a portable generator to power my whole house?

Yes, but you must have a licensed electrician install a manual transfer switch or an interlock kit. This legally and safely connects the generator to your breaker panel while automatically disconnecting your house from the grid so you don't electrocute utility workers.

Are solar generators (power stations) good for home backup?

Solar generators (like EcoFlow or Bluetti) are excellent for short-term outages. They are silent, emit no carbon monoxide (meaning they can sit inside your living room), and require no maintenance. However, unless you have thousands of watts of solar panels to recharge them, their batteries will deplete rapidly if running heavy loads like AC or well pumps.