NEC Dwelling Service Load Calculator (220.82)

Size a single-family 120/240 V service two ways — the Standard method (NEC 220 Part III) and the Optional method (220.82) — and take the smaller compliant result.

  1. Enter the dwelling basics Fill in "Conditioned area" in ft² and "Small-appliance circuits" (minimum 2) plus "Laundry circuits" (each counted at 1500 VA). The area drives the 3 VA/ft² general lighting load under NEC 220.12.
  2. Add the major appliances Set "Range" and "Dryer" in kW (enter 0 for none), then list each fastened-in-place unit under "Fastened-in-place appliances" with its name and VA. Four or more such appliances get a 75% demand factor per 220.53.
  3. Enter HVAC and special loads Fill in "Cooling", "Heating", and "Heat pump compressor" in VA, plus "EV charging" (continuous VA) and any "Other loads". The larger of heating vs cooling is applied per 220.60.
  4. Calculate and compare both methods Press Calculate to see the Standard (220 Part III) and Optional (220.82) results side by side as recommended service amps, each derived by dividing total VA by 240 V (220.5).

What size electrical service do I need for a 1,500 sq ft house?

Enter 1,500 in the Conditioned area field with your actual appliances; the calculator runs both the Standard method (NEC 220 Part III) and the Optional method (NEC 220.82) and shows recommended service amps for each. A typical all-electric 1,500 sq ft home commonly lands at a 100 A or 150 A service, but the result depends on your range, dryer, HVAC, and EV loads. Take the smaller compliant rating and confirm with your AHJ.

What is the difference between the standard and optional dwelling load methods?

The Standard method follows NEC 220 Part III, applying separate demand factors such as 220.42 for general lighting, 220.53 for fastened-in-place appliances, and 220.55 for the range. The Optional method under 220.82 instead takes the first 10 kVA at 100% and the remainder at 40%, with heating or air conditioning added separately. This calculator computes both so you can use the smaller compliant service size.

How is the neutral load sized for a dwelling service?

The calculator estimates the neutral using NEC 220.61, which is based on the maximum unbalanced load between the ungrounded conductors and the neutral. The estimate is simplified: 240 V-only loads such as the water heater and most HVAC carry no neutral. For existing dwellings use 220.83 and for multi-family use 220.84 — both are separate calculations not covered here.

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