Home electrical load calculator
Enter your home size and the big electric appliances. You get the estimated demand in amps and how it compares with a 100, 150, or 200 amp service.
Enter your home size in square feet
Method: NEC 220.82, the optional calculation for existing dwellings. Square footage uses outside dimensions and excludes garages, porches, and unfinished space. Electric dryers count at a 5,000 W minimum (NEC 220.54). Local rules and code editions differ, and an electrician must confirm any real service sizing.
How this calculator works
This follows the NEC 220.82 optional method for dwellings. It adds 3 volt-amps per square foot for general lighting and receptacles, two 1,500 VA small-appliance circuits, and a 1,500 VA laundry circuit. Then it adds the nameplate rating of fixed appliances. The first 10,000 VA counts in full and the rest counts at 40 percent. Finally, it adds the single largest of the air conditioner or electric heat, and divides by 240 volts to get amps.
The method applies to services of 100 amps or more. It is a planning estimate, not a permit-ready calculation.
Frequently asked questions
How many amps does my house need?
Many homes land between 100 and 200 amps. Add up your size and the big electric loads (dryer, water heater, oven, air conditioning, electric heat, EV charger) in this calculator to see where you fall.
What is the NEC optional method?
NEC 220.82 is a shortcut calculation for dwellings. It applies demand factors so that the first 10,000 VA counts in full and everything after counts at 40 percent, then adds the largest heating or cooling load.
Is this calculation good enough to size a new panel?
It is a good planning check, but a licensed electrician or your local inspector does the official calculation. They also account for local code editions and the actual appliances in your home.
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Last updated October 2026. Reviewed by the Fix or Hire editorial team. Estimates only, not a quote.