Compute service demand load using the NEC 2023 optional method (single-family 220.82), multi-family demand factors (220.84), or general lighting demand factors (220.42). Instant results with article citations.
This tool implements three of the most common NEC 2023 service demand methods. Every result is calculated client-side with the exact factors from Article 220 — no API call, no account needed.
The optional method sums all connected load and applies 100 % to the first 10 kVA and 40 % to the remainder. The largest of A/C or heat is added at 100 %, and small-appliance/laundry circuits are credited at 1,500 VA each.
For multi-family services, after computing each unit's load per the standard method, table 220.84 applies a demand factor that scales from 35 % (10 units) down to 23 % at 42+ units. This calculator returns the table-derived demand for the unit count entered.
Applies to non-dwelling general lighting. First 12,500 VA at 100 %, then specific occupancy-dependent factors. Use this for office, retail, and assembly buildings where lighting is the dominant load.
NEC 220.82 is an alternative to the standard method (Part III of Article 220) that simplifies single-family dwelling service calculation. Total all general, small-appliance, laundry, fixed-appliance, range, dryer, and water-heater loads — apply 100 % to the first 10 kVA and 40 % to the remainder. Add the larger of A/C or heating at 100 %.
Yes. For all-electric dwellings the heat load is typically dominant, and 220.82(C) applies its 100 % factor on the largest of A/C or heat. If your dwelling has heat pump + supplemental heat, take the sum.
EV charging loads under 220.57 are added at 100 % for the first dwelling EVSE (up to 7,200 VA) and at 220.57(B) for multi-EVSE. This tool currently includes EVSE as a fixed-appliance line — for a full EV-load breakdown use the dedicated NEC Load Calculator.
Yes. NEC 230.79(C) requires a minimum 100-A service for any one-family dwelling, regardless of calculated load. The recommendation column reflects this floor.