Residential electrical load calculator

Enter the living area and the big loads. See the calculated load in VA, the amps at 240 V and the service size, by the NEC Article 220 standard method or the optional method, with every demand factor shown.

3 VAPer sq ft of living area

2 methodsStandard and optional

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Method

Living area, outside dimensions

sq ft

Leave out open porches, garages and unfinished spaces that can't be finished later.

Small-appliance circuits (kitchen, dining)

circuits

The NEC requires at least 2.

Laundry circuits

circuits

Electric range or cooktop + oven

Nameplate kW. 0 for gas.

Electric dryer

Nameplate kW. 0 for gas.

Water heater

0 for gas.

Dishwasher

Disposal

Built-in microwave

Other fastened-in-place appliances, total

Compactor, attic fan, well pump and the like. Each 500 W or 1/4 hp and up.

How many of those

appliances

Air conditioning or heat pump

Volts × the nameplate MCA or RLA. A 3-ton unit is often 4,000 to 6,000 VA.

Electric heat (strips, baseboard, furnace)

EV charger

Nameplate watts, for example 48 A × 240 V = 11,520 W. 0 for none.

Other loads at 100% (hot tub, shop, pool pump)

Largest motor

Leave at 0 to use the air conditioner. Standard method only.

Service size

150 A

30,875 VA calculated, 128.6 A at 240 V

30,875 VACalculated load

128.6 AAmps at 240 V

Standard, Part IIIMethod

This is a planning number. Section numbers shift between NEC editions, and some areas use the IRC's own load rules. The NEC as adopted where you work, the utility and the inspector govern the service size. Service work is for a licensed electrician.

How we got this

General lighting2,000 sq ft × 3 VA = 6,000 VANEC 220.12. Covers lighting and every general-use receptacle.
Small-appliance and laundry3 circuits × 1,500 VA = 4,500 VANEC 220.52(A) and (B).
Demand on the first two10,500 VA: first 3,000 at 100% + 7,500 × 35% = 5,625 VANEC Table 220.42, dwelling units.
Fastened-in-place appliances8,000 VA × 75% (4 appliances) = 6,000 VANEC 220.53. Ranges, dryers, heating, AC and EV chargers never count here.
Dryer5,000 W nameplate, at least 5,000 = 5,000 VANEC 220.54.
Range12 kW is 12 kW or less: 8,000 VANEC Table 220.55, Column C, one appliance.
Heating or coolinglarger of AC 5,000 and heat 0 = 5,000 VANEC 220.60: they do not run at the same time, so only the larger counts.
Largest motor5,000 VA × 25% = 1,250 VANEC 220.50 and 430.24.
Calculated load30,875 VA ÷ 240 V = 128.6 A
Service size150 A

Load	Connected VA	Rule	Counted VA
General lighting and receptacles	6,000	Table 220.42
Small-appliance and laundry	4,500	Table 220.42
after demand	10,500		5,625
Fastened-in-place appliances	8,000	75%	6,000
Dryer	5,000	5,000 min	5,000
Range	12,000	Col. C	8,000
Heat or AC, larger	5,000	100%	5,000
25% of largest motor	5,000	25%	1,250
Total			30,875

Sources: EC&M, One-Family Dwelling Unit Load Calculations (Mike Holt); EC&M, Dwelling Unit Calculations (Mike Holt): 220.12, 220.52 and the optional method; IAEI Magazine, Residential Service Calculations in the National Electrical Code (Christel Hunter); Leviton Captain Code 2023, 220.53 and 220.57 EVSE load (NEC text reprinted); Mike Holt forum, 2011 NEC Annex D Example D1(a) (78 A, 14,550 VA neutral); IAEI Magazine, Overcurrent Protection Part 2 (NEC 240.6 standard ratings); Open Exam Prep, Appliance, range and dryer load (Table 220.55 Column C, 8 kW, Note 1; numbered 120.55 in the 2026 NEC); NFPA 70, National Electrical Code (Chapter 9, Table 8; 240.4(D)). Checked 2026-10-08.

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Key takeaways

The standard method adds 3 VA a sq ft and 1,500 VA per kitchen and laundry circuit, takes the first 3,000 VA at 100% and the rest at 35%, then adds appliances, range, dryer, the larger of heat or AC, and 25% of the largest motor.
The optional method takes the first 10,000 VA of everything but heat and AC at 100% and the rest at 40%. It usually gives a smaller service.
Divide the total by 240 V for amps, then go up to the next service size. A one-family house needs at least 100 A.

How a residential load calculation works

Adding up every breaker in the panel gives a number far bigger than the house will ever draw, because nobody runs the oven, dryer, water heater, heat and every light at once. NEC Article 220 gives two ways to account for that (the 2026 NEC moves the same rules to Article 120, so 220.55 becomes 120.55; check which edition your area has adopted), and both end in a number of volt-amperes (VA) you divide by 240 V to get amps.

The standard method, in Part III of Article 220, works through the house one kind of load at a time and applies a demand factor to each. The optional method, in 220.82, lumps almost everything together and applies one factor to the lot. Both are allowed for a one-family house; the optional method has a couple of conditions, covered below.

Use the calculator for a new house, an addition, a panel upgrade, or to check whether an existing service can take an EV charger, a heat pump or a hot tub. It shows each step so you can put it on the permit application or hand it to the inspector.

The standard method, step by step

General lighting and receptacles. 3 VA a sq ft of living area, measured to the outside of the walls (220.12). Leave out open porches, garages and spaces that can't be finished later. This covers every light and general-use receptacle in the house.
Small-appliance and laundry circuits. 1,500 VA for each kitchen and dining small-appliance circuit, at least two, and 1,500 VA for the laundry circuit (220.52).
Demand on those two. Add them together. The first 3,000 VA counts at 100%, the next part up to 120,000 VA at 35%, and anything above that at 25% (Table 220.42).
Fastened-in-place appliances. Water heater, dishwasher, disposal, built-in microwave, compactor and the like, each 500 W or 1/4 hp or more. If there are four or more, take 75% of their total (220.53). Ranges, dryers, heating, air conditioning and EV chargers never go in this group.
Dryer. 5,000 VA or the nameplate, whichever is larger (220.54).
Range. One range up to 12 kW counts as 8,000 VA (Table 220.55, Column C). Above 12 kW, add 5% for each kW, or major fraction of a kW, over 12 (Note 1).
Heating or air conditioning. Only the larger of the two, because they do not run together (220.60).
EV charger. 7,200 VA or the nameplate, whichever is larger, at 100% (220.57 in the 2023 NEC).
Other loads. Hot tubs, shop equipment, pool pumps and other specific loads at their full rating.
Largest motor. Add 25% of the biggest motor, usually the air conditioner (430.24).

Load	How it counts	NEC
Lighting and receptacles	3 VA a sq ft	220.12
Small-appliance circuits	1,500 VA each, at least 2	220.52(A)
Laundry circuit	1,500 VA	220.52(B)
Lighting demand	3,000 at 100%, to 120,000 at 35%, rest 25%	Table 220.42
4 or more fixed appliances	75% of the total	220.53
Dryer	5,000 VA or nameplate	220.54
Range, 12 kW or less	8,000 VA	Table 220.55, Col. C
Heat vs AC	The larger only	220.60
EV charger	7,200 VA or nameplate	220.57 (2023)
Largest motor	+25%	430.24

Worked examples

A small house: NEC Annex D, Example D1(a). 1,500 sq ft, a 12 kW range and a 5.5 kW dryer, gas everything else.

1,500 × 3 = 4,500 VA, plus 3 circuits × 1,500 = 4,500 VA, makes 9,000 VA. Demand: 3,000 + 6,000 × 35% = 5,100 VA. Add the range at 8,000 and the dryer at its 5,500 nameplate: 18,600 VA. 18,600 ÷ 240 = 77.5 A, which the NEC example rounds to 78 A. The service still has to be at least 100 A.

A typical 2,000 sq ft all-electric house. 12 kW range, 5 kW dryer, 4,500 W water heater, 1,200 W dishwasher, 800 W disposal, 1,500 W microwave, 5,000 VA air conditioner, gas heat.

Lighting and circuits: 6,000 + 4,500 = 10,500 VA, demand 3,000 + 7,500 × 35% = 5,625 VA
Four fixed appliances: 8,000 × 75% = 6,000 VA
Dryer 5,000, range 8,000, AC 5,000, 25% of the AC 1,250
Total 30,875 VA ÷ 240 = 128.6 A, so a 150 A service

Add a 48 A EV charger (11,520 W) and the total becomes 42,395 VA, 176.6 A: a 200 A service.

IAEI's 2,900 sq ft example. Four small-appliance circuits, an 11 kW range, a 5 kW dryer, a hot tub, a Level 2 charger, water heater, dishwasher, disposal and microwave, a 6,000 VA air conditioner and gas heat. The standard method came to 47,520 VA, 198 A, a 200 A service. That article was written before the 2023 rule that keeps EV chargers out of the 75% group; with the charger counted at 100% the same house comes to 49,320 VA, 205.5 A, and needs a 225 A service.

The optional method (220.82)

The optional method is shorter and usually gives a smaller answer. It is only for a dwelling served by a single 120/240 V or 208Y/120 V set of 3-wire conductors with an ampacity of 100 A or more.

Add up the general loads at their nameplate: 3 VA a sq ft, 1,500 VA per small-appliance and laundry circuit, and every appliance that is fastened in place or on its own circuit, including the range, dryer and water heater. Leave out heating and air conditioning.
Take the first 10,000 VA at 100% and the rest at 40%.
Add the largest of: the air conditioning at 100%, a heat pump at 100% (with 65% of its backup strips), electric heat at 65% if there are fewer than four separately controlled units, or at 40% if there are four or more.

The 2,000 sq ft house above comes to 35,500 VA of general load: 10,000 + 25,500 × 40% = 20,200 VA, plus the 5,000 VA air conditioner, is 25,200 VA, 105 A. That is a 125 A service by the optional method against 150 A by the standard method.

2,000 sq ft example	Standard	Optional
Calculated load	30,875 VA	25,200 VA
Amps at 240 V	128.6 A	105 A
Service	150 A	125 A

From amps to a service size

Divide the calculated load by 240 V. Then go up to a service size you can buy. The NEC lists standard breaker ratings in 240.6(A): 100, 110, 125, 150, 175, 200, 225, 250, 300, 350 and 400 A, among others. Residential panels are most often 100, 125, 150, 200, 225 or 400 A, so the calculator picks the next of those. A one-family house needs a service disconnect of at least 100 A however small the calculated load (230.79(C)).

Leave room. A calculation that lands at 190 A on a 200 A service has nothing left for the heat pump or second EV charger the owner adds in five years. Many electricians size up when the number is close, and some utilities set their own rules for what they will connect.

Calculated amps	Common service
Up to 100 A	100 A (the minimum for a house)
100.1 to 125 A	125 A
125.1 to 150 A	150 A
150.1 to 200 A	200 A
200.1 to 225 A	225 A
225.1 to 400 A	400 A

Adding an EV charger, heat pump or hot tub

Most load calculations today are for one new load on an old service. Run the calculator with the house as it is, then add the new load and see where it lands.

EV chargers count at the larger of 7,200 VA or the nameplate, at 100%. A 48 A charger is 11,520 VA, which on its own is 48 A at 240 V.
Heat pumps replace both the heating and cooling line. Use the compressor plus the backup strips if both can run together.
Hot tubs and spas go in at their full rating as other loads.
Induction ranges over 12 kW add 5% of 8 kW for every kW above 12.

If the result is over the existing service, the choices are a service upgrade, moving gas appliances to stay gas, or an energy management system that keeps loads from running together.

The NEC and the inspector governThis is a planning calculation. Section numbers shift between NEC editions, some areas use the IRC's own rules, and the utility sets its own requirements. The NEC as adopted where you work and the local inspector decide the service size, and service work is for a licensed electrician.

When you have the size, build the estimate in Koira with the panel, meter base, conductors and labor as their own lines. For the wire to a far load, use the voltage drop calculator; for the raceway, the conduit fill calculator.

Last checked October 8, 2026. More for your trade: how electricians run on Koira.

FAQ

How do I calculate the electrical load for a house?

By the NEC standard method: 3 VA a sq ft plus 1,500 VA per small-appliance and laundry circuit, with the first 3,000 VA at 100% and the rest at 35%. Add fixed appliances (75% if four or more), the dryer (5,000 VA minimum), the range (8,000 VA up to 12 kW), the larger of heat or AC, any EV charger and 25% of the largest motor. Divide by 240 for amps.

What size service do I need for a 2,000 sq ft house?

It depends on what is electric. With an electric range, dryer, water heater and central AC and gas heat, the standard method gives about 129 A, so a 150 A service. Add a 48 A EV charger and it rises to about 177 A, a 200 A service.

Is 100 amp service enough for a house?

For a small house with gas heat, range and water heater, often yes. The NEC's own Annex D example, 1,500 sq ft with an electric range and dryer, comes to 78 A. 100 A is also the minimum for a one-family house.

What is the difference between the standard and optional method?

The standard method applies a separate demand factor to each kind of load. The optional method in 220.82 takes the first 10,000 VA of everything but heat and AC at 100% and the rest at 40%, then adds the heating or cooling. The optional method usually gives a smaller service.

How much load does an EV charger add?

Under the 2023 NEC, 7,200 VA or the charger's nameplate, whichever is larger, at 100%. It can't be part of the 75% fixed-appliance group. A 48 A charger adds 11,520 VA.

Why does the range count as 8,000 VA when it is rated 12 kW?

Burners and ovens rarely all run at full power together. Table 220.55, Column C, lets one range of 12 kW or less count as 8 kW. Above 12 kW, add 5% for each kW over.

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