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Residential load calculator (NEC)

Work out a one-family dwelling’s calculated load and minimum service size by the standard or optional method, edition by edition, from NEC 2017 to the new 2026 Article 120.

Calculated with electrician.wiki · https://electrician.wiki/calculators/residential-load/

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How to use this calculator

Choose the code edition your jurisdiction enforces, then the method. Enter the floor area (outside dimensions of the habitable space, excluding open porches, garages and unfinished areas) and the nameplate ratings of the fixed appliances. Set gas appliances to zero. The calculator shows every line of the calculation with the section it comes from, the result in volt-amperes and amperes, the minimum service, and what the same home gives under the other edition.

What changed in the 2026 NEC

  • Load calculations moved from Article 220 to Article 120. Most section numbers keep their suffix: 220.82 is now 120.82 and Table 220.55 is Table 120.55.
  • The dwelling unit load fell from 3 to 2 VA/ft² (120.41), reflecting LED lighting and measured household loads. The minimum number of general-lighting branch circuits is still counted at 3 VA/ft² (new 120.13).
  • The optional method’s first block dropped from 10 kVA to 8 kVA at 100 %, and an EV charger is now added at 100 % outside the general load (120.82(D)).
  • 120.5(E) says a load calculation doesn’t have to count continuous loads at 125 %. The 125 % rule still applies when you size conductors and breakers.
  • EV chargers count at their nameplate rating in 2026 (120.57); the 2023 edition used the larger of 7,200 VA or the nameplate (220.57).

Read the full list on our 2026 NEC changes page, and check which edition your state uses on the NEC adoption map.

One home, four code editions

A 2,400 ft² all-electric home with a 12 kW range, 5 kW dryer, 4.5 kW water heater, dishwasher and disposal, a 6 kVA heat pump with 10 kW of backup heat, and an 11.5 kW EV charger. Every number is computed by the calculator above.

The same all-electric home under each NEC edition
MethodNEC 2017NEC 2020NEC 2023NEC 2026
Standard method47,145 VA
196 A → 200 A		47,145 VA
196 A → 200 A		47,145 VA
196 A → 200 A		46,305 VA
193 A → 200 A
Optional method37,220 VA
155 A → 175 A		37,220 VA
155 A → 175 A		37,220 VA
155 A → 175 A		41,960 VA
175 A → 175 A

The 2026 cuts are real but smaller than the headline suggests: the lighting demand factors (3,000 VA at 100 %, the rest at 35 %) absorb most of the drop from 3 to 2 VA/ft². The optional method usually gives the smaller answer for large, appliance-heavy homes, because everything except heating and cooling shares one diversity factor.

Worked examples

A 1,500 ft² home with a 12 kW range and 5.5 kW dryer (NEC 2023, standard method)

The classic textbook dwelling: general lighting, two small-appliance circuits, one laundry circuit, a range and a dryer.

  1. 1. General lighting and receptacles: 1,500 ft² × 3 VA/ft² (220.41)

    4,500 VA

  2. 2. Small-appliance circuits: 2 × 1,500 VA (220.52)

    3,000 VA

  3. 3. Laundry circuit: 1 × 1,500 VA (220.52)

    1,500 VA

  4. 4. After demand factors: first 3,000 VA at 100 %, the rest at 35 % (25 % over 120 kVA) (Table 220.45)

    5,100 VA · 9,000 VA before demand

  5. 5. Clothes dryer: larger of 5,000 VA or nameplate (220.54)

    5,500 VA

  6. 6. Cooking (12 kW) (Table 220.55)

    8,000 VA · Column C, one range up to 12 kW: 8 kW

  7. 7. Current at 240 V, rounded to whole amperes (220.5(B))

    I=18,600VA240V=77.5A

By the standard method of the NEC 2023, this home calculates to 18,600 VA, 78 A at 240 V: a 100 A service.

The same home under NEC 2026

Only the general lighting line changes, from 4,500 VA to 3,000 VA.

  1. 1. General lighting and receptacles: 1,500 ft² × 2 VA/ft² (120.41)

    3,000 VA

  2. 2. Small-appliance circuits: 2 × 1,500 VA (120.52)

    3,000 VA

  3. 3. Laundry circuit: 1 × 1,500 VA (120.52)

    1,500 VA

  4. 4. After demand factors: first 3,000 VA at 100 %, the rest at 35 % (25 % over 120 kVA) (Table 120.45)

    4,575 VA · 7,500 VA before demand

  5. 5. Clothes dryer: larger of 5,000 VA or nameplate (120.54)

    5,500 VA

  6. 6. Cooking (12 kW) (Table 120.55)

    8,000 VA · Column C, one range up to 12 kW: 8 kW

  7. 7. Current at 240 V, rounded to whole amperes (120.5(B))

    I=18,075VA240V=75.3A

By the standard method of the NEC 2026, this home calculates to 18,075 VA, 75 A at 240 V: a 100 A service.

Heat pump with 15 kW of supplemental heat (NEC 2023, optional method)

The compressor counts at 100 % and the backup heat at 65 %, compared with the other heating and cooling options.

  1. 1. General lighting and receptacles: 2,000 ft² × 3 VA/ft² (220.82(B))

    6,000 VA

  2. 2. Small-appliance and laundry circuits at 1,500 VA each (220.82(B))

    4,500 VA

  3. 3. Nameplate of appliances (cooking, dryer, water heater, dishwasher, others) (220.82(B))

    22,700 VA

  4. 4. General load after demand: first 10 kVA at 100 %, the rest at 40 % (220.82(B))

    19,280 VA · 33,200 VA before demand

  5. 5. Heat pump at 100 % plus supplemental heat at 65 % (the largest heating/cooling option) (220.82(C))

    15,510 VA · left out: air conditioning at 100 % = 5,760 VA

  6. 6. Current at 240 V, rounded to whole amperes (220.5(B))

    I=34,790VA240V=145.0A

By the optional method of the NEC 2023, this home calculates to 34,790 VA, 145 A at 240 V: a 150 A service.

From calculated load to service size

Round the current to whole amperes (fractions below 0.5 may be dropped), then pick the next standard service rating. A one-family dwelling needs at least a 100 A service. For the service-entrance or main feeder conductors of a dwelling, the NEC allows conductors rated at 83 % of the service rating (310.12): a 200 A service can use conductors with an ampacity of at least 166 A. Use the wire size calculator for the conductors and the voltage drop calculator for long service runs.

Common mistakes

  • Adding heat and air conditioning together. They never run at the same time, so the code counts only the larger (noncoincident loads).
  • Forgetting 25 % of the largest motor in the standard method, usually the A/C compressor.
  • Using the dryer’s nameplate when it is below 5,000 VA. The standard method uses 5,000 VA or the nameplate, whichever is larger.
  • Counting a range at its full nameplate in the standard method. Table 220.55 Column C allows 8 kW for one range up to 12 kW.
  • Applying 2026’s 2 VA/ft² to the branch-circuit count. The number of general-lighting circuits is still based on 3 VA/ft².
  • Treating the result as the breaker size for an EV circuit. The EV branch circuit is sized at 125 % of the charger’s rating because it is a continuous load.

Method and verification

The calculator follows the standard method (Article 220 Part III, Article 120 Part III in 2026) and the optional method for one dwelling (220.82 / 120.82) line by line, with edition-specific values for the dwelling unit load, the optional-method block, and EV chargers. It is tested against the worked examples in the NEC’s Informative Annex D for both 2023 and 2026, including the one-family standard method (18,600 VA and 78 A under 2023; 18,075 VA and 75 A under 2026) and three optional-method examples, plus properties such as “more floor area never lowers the load”.

Covers single one-family dwellings. Multifamily, existing-dwelling (220.83/120.83) and non-dwelling calculations are coming next. Updated 2026-10-14. Corrections log.

Questions people ask

How do you calculate the load for a house?
Add the general lighting load (floor area × 3 VA/ft², or 2 VA/ft² under the 2026 NEC), 1,500 VA for each small-appliance and laundry circuit, apply the demand factors, then add the range, dryer, fixed appliances, the larger of heating or cooling, and any EV charger. Divide by 240 V for the current.
What changed for load calculations in the 2026 NEC?
They moved to Article 120. The dwelling unit load dropped to 2 VA/ft², the optional method’s first block dropped to 8 kVA, EV chargers count at nameplate, and 120.5(E) says the calculation need not add 125 % for continuous loads.
Should I use the standard or optional method?
Either is allowed for a one-family dwelling. The optional method usually gives a lower result for larger homes with many appliances; the standard method can be lower for small homes with few appliances. Many electricians run both.
Is 100 A enough for my house?
If the calculated load is under 100 A, a 100 A service meets the code minimum. Many homes with electric heat, an EV charger or a heat pump calculate to 150–200 A or more.
Do I add 125 % for continuous loads in a load calculation?
Not under the 2026 NEC (120.5(E)). Continuous loads still need conductors and breakers sized at 125 % of the continuous part when you size the circuit or feeder.