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NEC Load Calculator

Enter the home’s living area, the nameplate loads of the large appliances and the air conditioning and heating. The calculator applies the NEC optional method for dwellings and gives the calculated load, the current at 240 V and the smallest standard service size.

Your numbers

A 32 A, 240 V charger is 7,680 VA. The 2026 method adds it at 100%, outside the demand factor.

Result

How we calculate it

The optional method adds the general lighting and receptacle load (3 VA per square foot in the 2023 code), 1500 VA for each small-appliance and laundry circuit, and the nameplate rating of the fixed appliances. The first 10,000 VA counts at 100% and the rest at 40%.

Then the larger of the cooling load (100%) and the electric heating load (65%, or 40% for four or more separately controlled units) is added, because they are not used together. The total in VA divided by 240 V is the service current.

The smallest standard breaker size at or above that current, and not under 100 A, is shown as the minimum service size. With the default values the calculated load is about 26,500 VA, or 110 A, so the minimum service is 125 A.

Assumptions and limits

  • This is a planning estimate, not electrical advice. Wiring must follow the electrical code adopted where you live, and a licensed electrician or permit inspector decides what is safe for your job.
  • The 2026 option (2 VA per square foot, first 8,000 VA at 100%, EV charger added at 100%) was confirmed against two published summaries of the new section 120.82, not against the NFPA text. Many places have not adopted the 2026 edition yet, so use the edition your local authority has adopted.
  • This is the optional dwelling method for a single home. Heat pumps with supplemental heat, large motors, pools and multi-family buildings need a full calculation by an electrician, and in the 2023 method an EV charger must be added as a fixed appliance.

Frequently asked questions

What is the NEC optional method?

A shortcut in the electrical code for working out the service size of a home. It applies a demand factor to the general and appliance loads, since not everything runs at once, and adds the larger of heating or cooling.

How do I know what size electrical service I need?

Run a load calculation. Most new homes need 100 A at the least and many get 200 A. The calculation, local code and the utility decide.

Why are heating and cooling not both added?

The code treats them as non-coincident: you will not run the air conditioner and electric heat at the same time, so only the larger one counts.

What if the nameplate is in amps?

Multiply the amps by the voltage to get VA: for example a 30 A, 240 V dryer is 7,200 VA. Use the label values, not typical values.

Should I add an EV charger?

Yes, a Level 2 charger is a large continuous load. It is not in this simple calculation; ask an electrician to add it in a full calculation.

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Worked example (a fixed example using the starting numbers, it does not change as you type)

Inputs: NEC edition = NEC 2023 (section 220.82); Living area (square feet) = 2400; Small-appliance and laundry circuits = 3; Electric range or cooktop and oven (VA) = 12000; Electric clothes dryer (VA) = 5000; Water heater (VA) = 4500; Other fixed appliances: dishwasher, disposal, motors (VA) = 3000; Air conditioning (VA) = 6000; Electric space heating (VA) = 0; Electric heat is = Fewer than four separately controlled units (65%).

  • Calculated load 26,480 VA
  • Service current at 240 V 110.3 A
  • Minimum service size 125 A
  • General and appliance load 36,200 VA
  • After demand factor 20,480 VA
  • Heating or cooling used 6,000 VA
  • Which one Air conditioning

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Last reviewed: . Formulas and assumptions are described on our methodology page. For information only; not professional advice.