Calculate My Home
Units

Electrical Load Calculator

Enter the floor area and your big appliances to get the calculated load in VA, the amps at 240 V and whether a 100, 150 or 200 A service covers it.

Units
sq ft

Outside dimensions, every floor, without an open porch or an unfinished garage.

circuits

Kitchen and dining 20 A outlet circuits, at least 2.

circuits

Fastened-in-place appliances

  • W
  • W
  • W
  • W

Enter the wattage on each nameplate. The values filled in are placeholders, not your appliances.

W

Counted at 5,000 W or the nameplate, whichever is larger (220.54).

kW

Nameplate kW; 0 for gas. Up to 27 kW (Table 220.55).

W

Furnace, baseboard, heat strips; 0 for gas.

VA

Volts × amps from the outdoor unit.

W

EV charger, hot tub, workshop tools. Counted at 100%, no demand factor.

Calculated load at 240 V

123.4A

29,625 VA by the NEC standard method. A 150 A service covers it; the smallest standard rating that does is 125 A.
Calculated load
29,625VA
Minimum service
125A
Common panel size
150A
100 A24,000 VA150 A36,000 VA200 A48,000 VA

Swipe sideways to see the whole drawing.

Lighting and outlets 5,625 VAAppliances 6,000 VADryer 5,000 VARange 8,000 VAAir conditioning 5,000 VA

Service size check

  • 100 A service 24,000 VA

    short by 5,625 VA

  • 150 A service 36,000 VA

    covers 29,625 VA

  • 200 A service 48,000 VA

    covers 29,625 VA

The math

  1. General lighting

    2,000 sq ft × 3 VA (220.41) = 6,000 VA

  2. Small appliance, laundry

    (2 + 1) × 1,500 VA (220.52) = 4,500 VA

  3. Lighting demand

    3,000 + 7,500 × 35% (Table 220.45) = 5,625 VA

  4. Appliances

    8,000 VA × 75%, four or more (220.53) = 6,000 VA

  5. Dryer

    larger of 5,000 W and 5,000 W (220.54) = 5,000 VA

  6. Range

    12 kW, Column C, 8 kW (Table 220.55) = 8,000 VA

  7. Heat or AC

    larger of 0 and 5,000 (220.60) = 5,000 VA

  8. Service current

    29,625 VA ÷ 240 V = 123.4 A

A one-family house needs at least a 100 A service (230.79(C)). Existing homes adding load can use the actual peak demand instead (220.87); ask your electrician.

NEC 2023 (NFPA 70): Article 220 Part III standard method, Tables 220.45 and 220.55, 240.6(A) ratings. Your state or city may adopt an older edition or add local amendments.

A service upgrade involves the utility, a permit and an inspection; the meter and service conductors are not DIY work. Most places require a permit and inspection for new circuits, and many only let a licensed electrician or the homeowner of a single-family house do the work. Turn the breaker off and test the wires dead before you touch them, and have a licensed electrician check anything you are unsure about.

A 2,000 square foot house with an electric range, an electric dryer, a water heater, three kitchen appliances and a 5,000 VA air conditioner has a calculated load of 29,625 VA, or 123.4 amps at 240 volts, under the NEC standard method. That fits a 125 amp service at minimum and a 150 amp panel comfortably. Add a 32 amp EV charger and the load reaches 155.4 amps, which calls for 200 amps.

How the electrical load is calculated

The standard method is Part III of NEC Article 220 (2023 numbering, as laid out by Electrician U). Each group of loads gets its own demand factor, because not everything in a house runs at once:

  1. General lighting and outlets: 3 VA per square foot of living area (220.41).
  2. Small-appliance and laundry circuits: 1,500 VA for each of the kitchen's 20 amp small-appliance circuits (at least two) and each laundry circuit (220.52).
  3. Lighting demand factor (Table 220.45): the sum of 1 and 2 counts 100% for the first 3,000 VA, 35% from 3,001 to 120,000 VA, 25% above that.
  4. Fastened-in-place appliances (water heater, dishwasher, disposal, built-in microwave): 100% of the nameplates, or 75% when there are four or more (220.53). Ranges, dryers, heating and air conditioning are counted separately.
  5. Dryer: 5,000 W or the nameplate, whichever is larger (220.54).
  6. Range: Table 220.55. One range of 8¾ to 12 kW counts as 8 kW; above 12 kW, add 5% of 8 kW for each kW or major fraction over 12. At 8¾ kW or less, Note 3 allows 80% of the nameplate.
  7. Heating or air conditioning, whichever is larger: they do not run together, so 220.60 lets you drop the smaller one.

Amps = (lighting demand + appliances + dryer + range + larger of heat or AC) ÷ 240 V

Worked example: the default house

  • General lighting: 2,000 sq ft × 3 VA = 6,000 VA
  • Two small-appliance circuits and one laundry: 3 × 1,500 = 4,500 VA, total 10,500 VA
  • Table 220.45: 3,000 + 7,500 × 35% = 5,625 VA
  • Appliances: 4,500 + 1,200 + 800 + 1,500 = 8,000 VA, four of them, × 75% = 6,000 VA
  • Dryer 5,000 VA, range 12 kW at 8,000 VA, air conditioning 5,000 VA (no electric heat)
  • Total: 5,625 + 6,000 + 5,000 + 8,000 + 5,000 = 29,625 VA ÷ 240 V = 123.4 A

The appliance wattages are typical placeholders; replace them with your nameplates. Electrician U's own example, a 1,500 sq ft house with a 12 kW range, 6 kW of heat, a 5,000 VA dryer and five appliances totaling 8,400 VA, comes to 30,400 VA and 126.7 A; enter those numbers and the calculator gives the same.

Lighting load by house size

General lighting plus two small-appliance circuits and one laundry circuit, after Table 220.45:

Living area3 VA per sq ftWith 4,500 VA of circuitsAfter demand factor
1,000 sq ft3,000 VA7,500 VA4,575 VA
1,500 sq ft4,500 VA9,000 VA5,100 VA
2,000 sq ft6,000 VA10,500 VA5,625 VA
2,500 sq ft7,500 VA12,000 VA6,150 VA
3,000 sq ft9,000 VA13,500 VA6,675 VA
4,000 sq ft12,000 VA16,500 VA7,725 VA

Doubling the floor area adds surprisingly little: most of a home's calculated load comes from the big appliances.

100, 150 or 200 amp service?

Divide the load by 240 V and round up to a standard rating from 240.6(A). The service may not be smaller than the calculated load (Electrician U cites 230.42), and 230.79(C) sets 100 A as the floor for a one-family dwelling. Switch the dryer off and set the range to 0 for gas, and the default house falls to 16,625 VA, 69.3 A: it still gets 100 A. The same 2,000 sq ft house with 15 kW of electric heat reaches 39,625 VA, 165.1 A, so 200 A. The calculator shows the smallest standard rating and the next of the common panel sizes, 100, 150, 200 and 400 A. Local rules can be stricter: Wisconsin's electric code, for example, requires 150 A for two-family dwellings.

What this method does not cover

  • Existing houses. 220.87 lets an electrician base an upgrade on a year of actual peak demand, times 125%, plus the new load. It often shows more spare room than the calculated method.
  • The optional method (Part IV) is a second, simpler calculation for dwellings; the service may be sized by either.
  • EV chargers, hot tubs and shop equipment are entered here at 100% of their rating with no demand factor. Check how your electrician counts an EV charger under 220.57.
  • Multifamily buildings use different demand factors.

Next steps

Size each new circuit with the breaker size calculator and the wire size calculator. Convert nameplates in amps or horsepower with the amp calculator. Feeding a detached garage or shop? Check the voltage drop on the feeder. All tools are on the electrical calculators page.