Electrical Load Calculator
Planning a panel upgrade or new construction? This calculator estimates your home's total electrical demand using the NEC optional method (Article 220.82) to determine the right service panel size.
Enter Your Measurements
Results
How to Use This Calculator
- Enter your home's total square footage.
- Enter the number of small appliance and laundry circuits.
- Enter wattages for major appliances (check nameplates).
- Enter your HVAC load (use the larger of heating or cooling).
- Review the recommended service panel size.
How Electrical Load Calculation Works
NEC Article 220.82 uses a simplified demand calculation for residential services. General loads (lighting and receptacles) get a demand factor — the first 10,000 VA at 100%, everything above at 40%, because not all loads run simultaneously. Electric ranges under 12kW use a fixed 8,000W demand value. HVAC uses only the larger of heating or cooling (they don't run at the same time). The total is divided by 240V to get the minimum service amperage.
Formula
General load = (Sq ft × 3) + (Small appliance circuits × 1500) + (Laundry × 1500). First 10,000 VA at 100%, remainder at 40%. Add range (8,000W demand for ≤12kW), dryer, HVAC, water heater, EV charger. Service amps = Total VA ÷ 240V.