Service Load Calculation (Residential)

Standard demand factors over lighting, appliances, range, dryer, HVAC; output minimum service ampacity.

Run the calculator

Example

You enter

Conditioned area (ft²) 2000
Small-appliance circuits (min 2) 2
Laundry circuits 1
Fixed appliances total (W) 6000
Range nameplate (W) 12000
Dryer nameplate (W; 5000 minimum) 5000
HVAC cooling (W) 5000
HVAC heating (W) 8000

You get

Total demand 34225 W
Required ampacity 142.6 A
Next standard service 150 A

Details, formula, and sources

Standard method per NEC 220.42 (general lighting demand factors) and 220.82 (optional dwelling-service); appliance loads per NEC 220.53.

NEC 2023 (NFPA 70). Article 220.

Free read-only access at nfpa.org/freeaccess.

Estimate. AHJ and licensed electrician govern. Verify against the NEC edition adopted in your jurisdiction.

Field names used by the API: area_ft2, small_appliance_circuits, laundry_circuits, fixed_appliances_W, range_W, dryer_W, hvac_cooling_W, hvac_heating_W, total_demand_W, required_A, next_standard_A

Voltage 240 V single-phase split for dwelling unless user suppliesANSI C84.1 nominal
Demand factor for first 3 kVA general lighting 100% (per NEC 220.42)NEC 2023