NEC Residential Load Calculator | Article 220 Dwelling Service Sizing

NEC Residential Load Calculator

Determine your home's total electrical demand and minimum service size per NEC Article 220 Standard Method.

NEC Article 220 Standard Method Service Sizing Permit Ready
Dwelling Unit Dimensions
Living area per NEC Table 220.12.
Min. two 20A circuits required per NEC 210.11(C)(1).
Dedicated 20A circuit required per NEC 210.11(C)(2).
Fixed Appliance Load
Qty kW
No items added
Dishwashers, water heaters, etc. (75% demand factor if 4+ units).
Cooking & Range Load
Qty kW
No items added
Calculated per NEC Table 220.55 (Column C).
Dryers
Qty kW
No items added
Min. 5.0 kW per unit required by NEC Table 220.54.
HVAC & Vehicle Charging Loads
Qty kW
No units added
Heating
Qty kW
No units added
Calculator uses the larger of total AC or Heating load.
Other Specified Loads
Qty kW
No items added

Calculated Results

Demand Load VA
- VA
Minimum Service Rating
-A
Recommended Panel Rating
-
Load Category Breakdown
Calculated using 2023 NEC Articles 220 and 230 for branch circuits, feeders, and services.

Professional Guide: NEC Residential Load Calculation

Determining the correct electrical service size for a dwelling unit is a critical step for safety and permit approval. Whether you are planning a panel upgrade, adding an EV charger, or sizing a new dwelling service, our NEC Residential Load Calculator streamlines this process by applying the complex demand factors found in NEC Article 220.

Understanding the "Standard Method" (Article 220, Parts II and III) is essential for professional electricians and inspectors. This service size calculator uses tiered demand factors for general lighting (3 VA per square foot) and specific calculations for appliances like ranges, water heaters, and clothes dryers to ensure your panel load calculation is accurate and code-compliant.

Related NEC Tools

Once you determine your service size, ensure your raceways are sized correctly with our NEC Conduit Fill Calculator.

Standard Method vs. Optional Method

The Standard Method is the most comprehensive way to size a residential service. It uses tiered demand factors for general lighting and specific demand tables for ranges and dryers. For homeowners asking "can my panel handle an EV charger?" or "do I need a 200 amp service upgrade?", this level of detail is necessary for a safe installation and reliable permit approval.

Frequently Asked Questions: Residential Load Calculation

How many amps does my house need? (100A vs. 200A)
Determining if you need a 100-amp, 150-amp, or 200-amp service depends on your total demand load. While 100-amp panels were standard for decades, modern homes with HVAC systems, electric vehicle (EV) charging, and high-wattage kitchen appliances often require a 200-amp service upgrade to remain NEC compliant.
Can I add an EV charger to my existing 100 amp panel?
An EV charger is a continuous load that must be calculated at 125% of its rating. If your existing demand load is already high, adding a 40A or 50A charger may trigger an NEC requirement for a panel upgrade or service size increase.
What counts as "Living Area" in a residential load calculation?
Per NEC Table 220.12, the 3 VA per square foot factor applies to all finished living spaces. You should exclude open porches, garages, and unfinished basements not intended for future habitation from your square footage calculation.
How are HVAC and A/C loads calculated together?
The NEC allows you to omit the smaller of either the air conditioning or the heating load, as they are non-coincident (they do not run at full capacity at the same time). Our NEC load calculator automatically selects the larger of the two at 100% demand.
Is this calculator for a permit or inspection?
Yes, this residential panel load calculator follows the Article 220 Standard Method, which is accepted by most AHJs (Authorities Having Jurisdiction) for residential permit applications. However, always verify with your local electrical inspector for specific requirements.
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