Calculation methodology
How the planning estimate works.
PanelLoadCalc uses National Electrical Code Article 220 demand factors to estimate a home's electrical service load. The result is a planning signal—not a permit calculation.
1. General lighting and receptacles
The NEC requires 3 VA per square foot for general lighting, plus defined kitchen and laundry circuits.
+ Small appliance circuits × 1,500 VA
+ Laundry circuit × 1,500 VA
2. Demand factors
The estimate applies demand factors because a home rarely uses every connected load at once.
Remainder: 35%
Why older services can become constrained
Homes once relied more heavily on gas cooking, water heating, clothes drying, and space heating. A 100A service could be sufficient for that equipment mix.
Today, a Level 2 EV charger, heat pump, induction range, electric dryer, and electric water heater can materially change the dwelling load. The calculator is designed to surface that constraint before a project reaches permitting or installation.
Important boundary
The calculator cannot inspect panel condition, conductor sizes, utility equipment, local amendments, or installation details. A licensed electrician must verify the final calculation and design.