Your panel
Use your best guess. "Not sure" is fine; an electrician can confirm from a photo.
Usually printed on the main breaker at the top of the panel.
A few older brands are commonly flagged for replacement.
Empty slots where a new breaker could go.
Used for lighting and outlet load, and to size a heat pump.
What your home has today
Select the large electric loads already in your home.
What you're planning to add
Select the upgrades you're considering.
How your load is calculated
NEC 220.83, the National Electrical Code method for adding loads to an existing home.
About this calculation
Electricians check whether an existing home can take new loads using NEC section 220.83. It adds up lighting and outlets (3 watts per sq ft), kitchen and laundry circuits, and the nameplate ratings of large appliances. Because not everything runs at once, the first 8,000 watts count fully and the rest count at 40%. When a heat pump or other new heating or cooling is added, that equipment counts fully on its own.
The total, divided by 240 volts, must not exceed your panel's rating. This tool flags anything above 80% as tight, to leave room for future needs.
An electrician may also use 12 months of your PG&E smart meter data to measure your actual peak demand (NEC 220.87). That often shows more room than this calculation.
Typical ratings used
About this planning tool
Is this a load calculation for a permit?
No. It's an educational estimate using typical appliance ratings. A permit calculation uses your actual equipment nameplates and is done by a qualified electrician.
What if my panel looks too small?
A full panel upgrade isn't the only answer. Smart panels, EV load management, circuit sharing devices, 120V heat pump water heaters and right-sized equipment can often avoid or delay one.
What helps an electrician review my panel?
A clear photo of the open panel with the main breaker and breaker labels visible, your planned upgrades, and 12 months of PG&E usage data. Attach the photo when you email your results.
About NRG Geek
NRG Geek is Robert Kelly's independent educational platform for practical Northern California guidance on solar, battery backup, EV charging, heat pumps and home electrification.
Every home is different. Panel condition, wiring, equipment choices and utility service all affect what an upgrade requires.
Privacy, legal and terms
How is my information used?
The Email My Results button opens your email app with your inputs and results. Nothing is sent until you send it. If you ask for personal guidance, Robert may follow up. NRG Geek does not sell your personal information.
Is this a safety inspection or guarantee?
No. Results are planning estimates only. They are not a permit load calculation, safety inspection, engineering design or guarantee. Electrical work should be done by a licensed electrician.
Third-party brands
Panel and equipment names are trademarks of their owners. NRG Geek is not affiliated with them.
Accuracy
Electrical codes, local requirements, PG&E rules and equipment ratings change over time. Verify important information before making financial or construction decisions.
Copyright
© 2026 NRG Geek. All rights reserved. This calculator and its educational content may not be reproduced without written permission.