How do I calculate the electrical load of a house?

For a service carrying the whole dwelling, IRC Table E3602.2: 3 VA per sq ft, plus 1,500 VA for each 20 A kitchen, dining and laundry circuit, plus the nameplate of fixed appliances. Take 100% of the first 10,000 VA and 40% of the rest, add the largest heating or cooling load, and divide by 240.

What size service does a 2,000 sq ft house need?

It depends on the appliances. With gas cooking, drying and water heating, a 1.2 kW dishwasher and 10 kW of cooling, the service table gives about 86 A, so the 100 A minimum governs. All-electric with the same cooling it is about 123 A, a 125 A service.

Is 100 amps enough for a house?

It is the code minimum for a one-family dwelling under IRC E3602.1. Whether it is enough depends on the calculated load: many gas-heated houses calculate below 100 A, and all-electric houses often above it.

What is the difference between the optional and standard load calculation?

The optional method, IRC Table E3602.2 and NEC 220.82, takes all loads at nameplate and discounts everything past 10,000 VA to 40%. The standard method, Table E3704.2(1), discounts only lighting and receptacle load and counts large appliances with their own factors. For houses with large fixed loads the optional method is usually lower.

How much load does an EV charger add?

Its nameplate rating as a fixed appliance. In the service table it falls into the part discounted to 40%, so a 9.6 kW charger adds about 3,840 VA, 16 A, to the calculated service load.

Do I need a 200 amp panel?

Only if the calculated load exceeds 175 A, or you are planning loads that will. A 200 A service is common but not a code requirement for a dwelling.

How much does a panel upgrade cost?

HomeAdvisor's guide, updated June 2026, gives $800 to $1,500 for a 100 A panel, $1,300 to $2,000 for 200 A and $2,000 to $4,000 for 400 A, without saying what those figures include.

Does this apply to my house?

Where the International Residential Code's electrical chapters are adopted, for one and two family dwellings. Many jurisdictions adopt the NEC directly; its Article 220 carries the same two methods.

Home › Electrical › Residential Electrical Load Calculator

Residential Electrical Load Calculator

IRC Table E3602.2 for the service, Table E3704.2(1) for a feeder

The residential code has two load calculations and they do not agree. The service table, the NEC's optional method, takes everything at nameplate and discounts it past 10,000 VA. The feeder table, the standard method, discounts only lighting. A 2,000 sq ft all-electric house comes out at 123 amps by the first and 145 by the second, a 125 amp service by one and a 150 by the other. This calculator runs both.

Minimum service for a one-family dwelling

Floor area

sq ft

Kitchen, dining and laundry circuits (20 A)

no.

Electric range or cooktop and oven (0 if gas)

Electric dryer (0 if gas)

Electric water heater

Dishwasher and disposal

Other fixed appliances (well pump, hot tub)

Electric vehicle charger

Air conditioning or heat pump

Electric space heat (strip or baseboard)

Use nameplate ratings in kilowatts, which are close enough to kVA for resistive appliances. Floor area is the outside dimensions of the living space, not garages or unfinished areas. Count every 20 A kitchen, dining and laundry receptacle circuit.

Specification summary

Generated from on . Reopen that address to reproduce these figures exactly.

Entered

Result

One house, two load calculations

Electrical panel prices

Per panel by amperage
Item	Low	High	Unit
100 A panel	$800	$1,500	panel
150 A panel	$1,300	$1,600	panel
200 A panel	$1,300	$2,000	panel
400 A panel	$2,000	$4,000	panel

Source: HomeAdvisor, how much does it cost to upgrade or replace an electrical panel. Last price check: September 13, 2026.

The source says it was updated using automation technology and reviewed by an editor, and does not say what its amperage table includes. It gives $518 to $2,192 for a panel replacement, $1,346 on average, which is below the low end of its own 150 and 200 A rows. Its headline reads 2025 on a page dated June 2026. A panel replacement is not the same job as a service upgrade, which can involve the utility, the meter and the service conductors.

Worked example

A 2,000 sq ft house with three 20 A kitchen and laundry circuits, a 12 kW range, 5.5 kW dryer, 4.5 kW water heater, 1.2 kW dishwasher and 10 kW of air conditioning.

Connected load. 6,000 VA lighting + 4,500 VA circuits + 23,200 VA appliances = 33,700 VA.
Service demand. 10,000 at 100% + 23,700 at 40% = 19,480 VA.
Add cooling. 19,480 + 10,000 = 29,480 VA, ÷ 240 = 122.8 A: a 125 A service.
Feeder table. Lighting 5,625 + appliances 5,700 + dryer 5,500 + range 8,000 + cooling 10,000 = 34,825 VA = 145.1 A.
Gap. 22 A more by the feeder table, enough to cross a standard rating.

Swap to 5 kW of cooling with 15 kW of strip heat and add a 9.6 kW car charger, and the service table gives 138 amps while the feeder table gives 206. The service method's 40 per cent factor absorbs large fixed loads that the feeder table counts in full.

The formula

Table E3602.2 for a service carrying the whole dwelling:

base = 3 VA × sq ft + 1,500 VA × circuits + fixed appliances demand = min(base, 10,000) + 0.40 × (base − 10,000) amps = (demand + largest heating or cooling) ÷ 240

3 VA a sq ft: general lighting and receptacles
1,500 VA: each 20 A small appliance and laundry circuit
fixed appliances: nameplate of ranges, ovens, dryers not on the laundry circuit, water heaters and other dedicated-circuit appliances
heating or cooling: the largest of: 100% of cooling or a heat pump without strips, 100% of the compressor plus 65% of strips, 65% of fewer than four electric heaters, 40% of four or more
100 A: the minimum service for a one-family dwelling, E3602.1

The feeder table, E3704.2(1), discounts lighting and circuits at 35 per cent past 3,000 VA, takes a dryer at 5,000 VA minimum and a 12 kW or smaller range at 8,000 VA, and adds the larger of heating or cooling at 100 per cent.

Why this page runs both tables

Load calculators online pick one method, rarely say which, and often mix the two.

The residential code carries both, the NEC's optional method for the service and its standard method for feeders, each bracketed to its NEC section. Running one house through both shows how far apart they land and in which direction.

The tables are read from Utah's 2021 adoption and confirmed identical in Virginia's.

One house, the service table against the feeder table
Step	Service, Table E3602.2	Feeder, Table E3704.2(1)
Lighting and receptacles, 3 VA a sq ft on 2,000 sq ft	6,000 VA	6,000 VA
Three 1,500 VA kitchen and laundry circuits	4,500 VA	4,500 VA
Demand on lighting and circuits	counted with appliances below	5,625 VA (100% of 3,000, 35% of the rest)
12 kW range	12,000 VA	8,000 VA (Table E3704.2(2), one appliance)
5.5 kW dryer	5,500 VA	5,500 VA
Water heater and dishwasher	5,700 VA	5,700 VA (100%, fewer than four)
Demand on everything above	19,480 VA (100% of 10,000, 40% of the rest)	applied line by line
10 kW air conditioning	10,000 VA	10,000 VA
Total	29,480 VA, 123 A	34,825 VA, 145 A

Read 2026-09-13. IRC 2021 Tables E3602.2, E3704.2(1) and E3704.2(2) as adopted in Utah; the arithmetic is this page's.

Download this table as CSV. Same cells as printed above, nothing added.

Two load calculations in one code, and the same house through both

The residential code sizes a service with Table E3602.2, whose bracket points to NEC 220.82, the NEC's optional method. A feeder that does not carry the whole dwelling uses Table E3704.2(1), bracketed to 220.42 through 220.60, the standard method. The demand factors are different in kind. The service method takes everything at nameplate and then discounts all of it past 10,000 VA:

The minimum subtotal for the loads above shall be 100 percent of the first 10,000 volt-amperes of the sum of the above loads plus 40 percent of any portion of the sum that is in excess of 10,000 volt-amperes.

The feeder method discounts only lighting and receptacle load, and more steeply:

100 percent of first 3,000 VA or less and 35 percent of that in excess of 3,000 VA.

One 2,000 sq ft all-electric house through both tables, IRC 2021 as adopted in Utah
Step	Service, Table E3602.2	Feeder, Table E3704.2(1)
Lighting and receptacles, 3 VA a sq ft on 2,000 sq ft	6,000 VA	6,000 VA
Three 1,500 VA kitchen and laundry circuits	4,500 VA	4,500 VA
Demand on lighting and circuits	counted with appliances below	5,625 VA (100% of 3,000, 35% of the rest)
12 kW range	12,000 VA	8,000 VA (Table E3704.2(2), one appliance)
5.5 kW dryer	5,500 VA	5,500 VA
Water heater and dishwasher	5,700 VA	5,700 VA (100%, fewer than four)
Demand on everything above	19,480 VA (100% of 10,000, 40% of the rest)	applied line by line
10 kW air conditioning	10,000 VA	10,000 VA
Total	29,480 VA, 123 A	34,825 VA, 145 A

The service method gives 123 amps and the feeder method 145. Both round up to the same standard service here, but the gap is 22 amps, and on a house near a rating boundary it decides between sizes.

And the code routes the whole house to the lower one.

The load for feeder conductors that serve as the main power feeder to a dwelling unit shall be determined as specified in Chapter 36 for services.

So the main feeder is sized as a service, but a feeder to a subpanel that carries most of the same appliances is sized by the feeder table and can come out larger than the service that supplies it. E3704.1 also says a feeder need not be larger than the service-entrance conductors.

Before adding a heat pump or car charger

Put the new load in and read the service line. A 9.6 kW charger added to a house already at 123 A by the service table raises it by 16 A after the 40 per cent factor, to about 139 A, which crosses from 125 to 150.

Electric heat has its own factors. Fewer than four separately controlled heaters count at 65 per cent; four or more at 40 per cent. A heat pump with strip heat counts the compressor at 100 per cent and the strips at 65.

The calculation is a minimum. It says what the code requires for the loads entered, not what a household will want in ten years, and the utility decides what it will supply to the meter.

The sources, and what this does not do

Read 2026-09-13.

Utah Residential Code 2021, Chapter 36 Services, International Residential Code 2021 as adopted with amendments in Utah, read through UpCodes with the jurisdiction and edition stated on the page. Sections E3602.1 to E3602.3 and Table E3602.2, minimum service load calculation, bracketed to NEC 220.82.

Utah Residential Code 2021, Chapter 37 Branch Circuit and Feeder Requirements, International Residential Code 2021 as adopted in Utah, read through UpCodes. Sections E3704.1 and E3704.2, Tables E3704.2(1) and E3704.2(2), bracketed to NEC 220.42 to 220.60.

Virginia Residential Code 2021, Chapter 36 Services, Read through UpCodes to confirm the Utah tables are the model text. Tables E3602.2 and E3704.2(1) identical to Utah's.

This is a code minimum, not a design. It does not add future loads such as an electric vehicle charger or a heat pump you have not bought yet, and it does not check what your utility will supply. Where your jurisdiction adopts the NEC directly, its edition governs.

Frequently asked questions

How do I calculate the electrical load of a house?: For a service carrying the whole dwelling, IRC Table E3602.2: 3 VA per sq ft, plus 1,500 VA for each 20 A kitchen, dining and laundry circuit, plus the nameplate of fixed appliances. Take 100% of the first 10,000 VA and 40% of the rest, add the largest heating or cooling load, and divide by 240.
What size service does a 2,000 sq ft house need?: It depends on the appliances. With gas cooking, drying and water heating, a 1.2 kW dishwasher and 10 kW of cooling, the service table gives about 86 A, so the 100 A minimum governs. All-electric with the same cooling it is about 123 A, a 125 A service.
Is 100 amps enough for a house?: It is the code minimum for a one-family dwelling under IRC E3602.1. Whether it is enough depends on the calculated load: many gas-heated houses calculate below 100 A, and all-electric houses often above it.
What is the difference between the optional and standard load calculation?: The optional method, IRC Table E3602.2 and NEC 220.82, takes all loads at nameplate and discounts everything past 10,000 VA to 40%. The standard method, Table E3704.2(1), discounts only lighting and receptacle load and counts large appliances with their own factors. For houses with large fixed loads the optional method is usually lower.
How much load does an EV charger add?: Its nameplate rating as a fixed appliance. In the service table it falls into the part discounted to 40%, so a 9.6 kW charger adds about 3,840 VA, 16 A, to the calculated service load.
Do I need a 200 amp panel?: Only if the calculated load exceeds 175 A, or you are planning loads that will. A 200 A service is common but not a code requirement for a dwelling.
How much does a panel upgrade cost?: HomeAdvisor's guide, updated June 2026, gives $800 to $1,500 for a 100 A panel, $1,300 to $2,000 for 200 A and $2,000 to $4,000 for 400 A, without saying what those figures include.
Does this apply to my house?: Where the International Residential Code's electrical chapters are adopted, for one and two family dwellings. Many jurisdictions adopt the NEC directly; its Article 220 carries the same two methods.

Check these numbers yourself

Utah Residential Code 2021, Chapter 36 ServicesIRC 2021 as adopted in Utah, read 2026-09-13 through UpCodes with the jurisdiction and edition stated on the page. Sections E3602.1 to E3602.3 and Table E3602.2.
Utah Residential Code 2021, Chapter 37IRC 2021 as adopted in Utah, read 2026-09-13. Sections E3704.1 and E3704.2, Tables E3704.2(1) and E3704.2(2).
Virginia Residential Code 2021, Chapter 36Read 2026-09-13 to confirm the tables match Utah's.
How Much Does It Cost to Upgrade or Replace an Electrical Panel?HomeAdvisor, reviewed by Salvatore Cutrona, updated 2026-06-17, read 2026-09-13.

How every figure here is verified: Sources & Method. Who builds this: About. Found something wrong? Tell us and it gets fixed or removed.

Figures on this page last checked against the source documents on 2026-09-13. Codes are amended locally; confirm against the edition your jurisdiction enforces.

Related calculators

Load calculations follow the 2021 International Residential Code as adopted in Utah, read on 13 September 2026, for one-family dwellings. Your jurisdiction may adopt the NEC directly, a different edition or amendments. A service upgrade involves the utility and a permit. Prices are HomeAdvisor's, not this site's.