PANEL LOAD
About this calculator
This panel load calculator estimates the total demand on a residential electrical service using the NEC 220 Part III "Standard Method." It applies 3 VA/ft² for general lighting and receptacles, 1500 VA per small-appliance and laundry circuit, then NEC 220.42 demand factors (100% of the first 3000 VA + 35% of the next 117,000 VA). Major appliances — range, dryer, water heater, HVAC, EV charger — are added at their nameplate or NEC-prescribed demand. The result is a service-size recommendation: 100 A, 150 A, 200 A, or 400 A. ESTIMATE ONLY — final service sizing must be done by a licensed electrician using the actual NEC 220 Part III or IV worksheet and verified by the local AHJ.
How to use this calculator
Enter the home's conditioned floor area in square feet (NEC 220.41 uses 3 VA/ft² for general lighting and receptacles — exclude open porches, garages, and unfinished basements/attics). Set the small-appliance circuit count (NEC 210.11(C)(1) requires at least 2 for kitchen/dining; most homes have exactly 2) and laundry circuit count (typically 1).
For each major electric appliance, enter the kW nameplate rating (set to 0 if you have the gas version). EV charger goes in as continuous draw (e.g., 7.7 kW for a 32A 240V Level 2). The calculator applies NEC demand factors and returns a recommended service size: 100 A, 150 A, 200 A, or 400 A.
Worked example
For a 2,000 ft² home with 2 small-appliance circuits, 1 laundry, electric range (12 kW), electric dryer (5 kW), electric water heater (4.5 kW), 5 kW heat pump, no EV:
General lighting: 2,000 × 3 = 6,000 VA. SA circuits: 2 × 1,500 = 3,000 VA. Laundry: 1,500 VA. Total lighting/SA/laundry: 10,500 VA.
Demand factor (NEC 220.42): first 3,000 VA at 100% + remaining 7,500 at 35% = 5,625. Lighting demand: 3,000 + 5,625 = 8,625 VA.
Range (12 kW): 8,000 VA per NEC 220.55 Table. Dryer (5 kW): 5,000 VA minimum. Water heater: 4,500 VA. Heat pump: 5,000 VA.
Total: 8,625 + 8,000 + 5,000 + 4,500 + 5,000 = 31,125 VA. Amps at 240V: 130 A. Recommended service: 150 A.
Add a 7.7 kW EV charger (continuous, ×1.25 = 9,625 VA) and total jumps to 40,750 VA = 170 A → 200 A service.
Common mistakes & waste factors
Forgetting to take the larger of heating or cooling. NEC 220.51 / 220.60 requires you include only the bigger of AC or heat pump, not both. Adding both double-counts the load.
Using nameplate watts on the EV charger without the 125% continuous factor. EV charging IS continuous (3+ hours) and triggers NEC 625.41 sizing. The calculator adds 25% automatically.
Including gas appliances at full electric load. If your dryer is gas (just a small motor for the drum), enter 0 — not 5 kW. Same for gas range, gas water heater.
Using the panel load to size individual circuits. The panel load calculation is for the whole service. Individual circuits are sized by their own nameplate load × 125% if continuous (use the breaker calculator).
Rules of thumb
NEC 220 Part III standard method, residential single-phase 240/120V.
General lighting: 3 VA/ft² × conditioned area.
Small-appliance circuits: 1,500 VA each, minimum 2.
Laundry: 1,500 VA × number of circuits.
Demand factor on lighting+SA+laundry: 100% of first 3,000 VA + 35% of remaining.
Range: 8,000 VA standard demand for ≤12 kW; +400 VA per kW above 12.
Service recommendations: ≤90 A → 100 A service, ≤130 A → 150 A, ≤180 A → 200 A, ≤320 A → 400 A.
Common questions
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