This calculates the load. It is not the load calculation your permit office accepts, and the local edition of the NEC may differ. 220.82 is an alternative to the standard method of Article 220, Part III. A licensed electrician or engineer prepares the calculation for the permit and the utility.

Maintained by BuildSolver · Updated October 22, 2026

Calculator · Electrical

Home electrical service load calculator

A 2,900 sq ft house with a range, dryer, water heater, hot tub, EV charger and a 6,000 VA air conditioner has 55,400 VA of general load. It heats with gas. The NEC 220.82 optional method counts the first 10,000 VA in full and the rest at 40 percent, 28,160 VA, then adds the cooling, 34,160 VA. At 240 V that is 142.3 A, so a 150 A service. This page does that sum for your house, handles a heat pump with supplemental heat, and compares the answer with the panel you have. The AC breaker size calculator sizes the circuit of one unit.

Enter the floor area, the number of small-appliance and laundry circuits, and the nameplate VA or watts of each electric appliance that is fastened in place or on its own circuit.
Enter the air conditioner or the heat pump compressor, any supplemental or space heating, and whether an interlock keeps the compressor off while the supplemental heat runs.
The result shows the load after demand, the current at 240 V and the service size. Enter the rating of the service or main breaker now to see the margin or the overload.

One dwelling on a 120/240 V 3-wire service, by NEC 220.82. A calculation of the load, not a load calculation accepted by a permit office. A licensed electrician and the local authority decide.

Floor area, sq ft

Outside dimensions of the living space. Leave out open porches, garages and spaces that cannot be finished later. Counted at 3 VA per sq ft.

Small-appliance circuits (20 A kitchen and dining)

At least two in a dwelling. Each counts 1,500 VA.

Laundry circuits (20 A)

Each counts 1,500 VA. A dryer on its own circuit is entered below, not here.

Range, cooktop or wall oven, VA or W

Nameplate rating of the range, or of the cooktop and the oven added together. 0 for gas.

Electric dryer, VA or W

Nameplate rating. 0 for gas, or if the dryer plugs into the laundry circuit above.

Electric water heater, VA or W

Nameplate watts. 0 for gas. A tank with two elements that run one at a time is the larger element.

Dishwasher, VA or W

Garbage disposal, VA or W

Built-in microwave, VA or W

Only a microwave that is fastened in place or on its own circuit. A countertop one on a kitchen receptacle is already in the small-appliance circuits.

EV charger, VA or W

Nameplate rating of the charger, for example 7,200 VA for a 30 A, 240 V unit.

Hot tub or spa, VA or W

Nameplate rating of the whole unit, heater and pumps.

Pool pump and equipment, VA or W

Nameplate volts x amps for a motor.

Well pump, VA or W

Nameplate volts x amps for a motor.

Other fixed appliances, VA or W (total)

Anything else fastened in place or on its own circuit that is not heating or cooling: second water heater, sauna, shop equipment. Add them together.

Air conditioner, VA

Nameplate volts x rated load amps of the condenser plus the air handler or furnace fan. 0 if the cooling is a heat pump entered below.

Heat pump compressor, VA

Nameplate of the outdoor unit. Enter a heat pump here, not also as an air conditioner.

Supplemental electric heat, W

Strip heat in the air handler of a heat pump, or central electric heat. 0 if none.

Compressor locked out when the supplemental heat runs

With a control that stops the compressor while the strip heat runs, the compressor is left out of the heat pump line.

Other electric space heating, W

Baseboard, wall heaters, radiant cable, electric furnace. Total nameplate. 0 if none.

Separately controlled electric heating units

A thermostat that runs its own heater is one unit. Four or more units are counted at 40 percent of the nameplate instead of 65 percent.

Electric thermal storage and other heating that runs steadily, W

Counted at 100 percent.

Rating of the service or main breaker now, A (optional)

To check a panel you have, for example 100, 150 or 200. Leave blank to only find the size needed.

Example result for the default inputs

2,900 sq ft dwelling, 120/240 V single phase, 3-wire. NEC 220.82 optional method.

Calculated load

34,160 VA

Current at 240 V

142.3 A

Service size

150 A

Calculation details
Lighting and receptacles	3 VA x 2,900 sq ft = 8,700 VA
Small-appliance and laundry circuits	5 circuits x 1,500 VA = 7,500 VA (4 small-appliance, 1 laundry)
Fixed appliances	Range, cooktop or oven 11,000, Dryer 5,000, Water heater 4,500, Dishwasher 1,200, Disposal 800, Microwave 1,500, EV charger 7,200, Hot tub or spa 8,000 = 39,200 VA
General load before demand	55,400 VA
General load after demand, 220.82(B)	10,000 VA at 100 percent + 40 percent x 45,400 VA = 28,160 VA
Heating and air conditioning, 220.82(C)	(1) Air conditioning, 100 percent: 6,000 VA. The larger counts: 6,000 VA, item (1).
Total calculated load	28,160 + 6,000 = 34,160 VA
Current at 240 V	34,160 VA / 240 V = 142.3 A
Service size	150 A, the smallest standard rating at or above 142.3 A (Table 240.6(A)).
Your 200 A service	Enough by this calculation: 57.7 A to spare, the calculated current is 71 percent of its rating.

For estimation purposes only. Consult a licensed engineer for final designs.

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How the service load is worked

The optional method adds up the general loads. It takes 100 percent of the first 10,000 VA and 40 percent of the rest, then adds one heating or air-conditioning load, the largest of six options. Divide by 240 V. The service is the next standard rating at or above that current, never under 100 A.

General load: 3 VA x sq ft + 1,500 VA x (small-appliance + laundry circuits) + nameplate of fixed appliancesNEC 220.82(B). The IAEI house is 3 x 2,900 = 8,700 VA of lighting and receptacles, 5 circuits x 1,500 = 7,500 VA, and 39,200 VA of fixed appliances, 55,400 VA in all. The area is the outside dimensions, without open porches, garages and spaces that cannot be finished later.
Demand on the general load: 10,000 + 0.4 x (general - 10,000)100 percent of the first 10 kVA and 40 percent of the remainder. 55,400 VA becomes 10,000 + 0.4 x 45,400 = 28,160 VA. Heating and air conditioning are left out of this step.
Heating and air conditioning: largest of 100% A/C, 100% heat pump, 100% compressor + 65% supplemental, 65% or 40% space heat, 100% storageNEC 220.82(C) takes the larger of items (1) through (6), not the sum, because the heating and the cooling do not run together. The IAEI house has a 6,000 VA air conditioner and gas heat. Space heating is 65 percent of the nameplate for fewer than four separately controlled units and 40 percent for four or more. A heat pump compressor is dropped from item (3) if the controls keep it from running with the supplemental heat.
Total and current: I = (demand + HVAC) / 240 V28,160 + 6,000 = 34,160 VA, and 34,160 / 240 = 142.3 A, the IAEI article's 142 A. Mike Holt's EC&M example divides by 240 V the same way: 89,398 VA is 372.5 A.
Service size: smallest standard rating at or above I, and at least 100 ATable 240.6(A) gives 150 A for 142.3 A, and 400 A for 372.5 A. A one-family dwelling disconnect is rated at least 100 A under 230.79(C), so a small house still gets 100 A. Table 240.6(A) lists sizes such as 110 A, so check which ratings the service equipment is made in.
Your panel: margin = rating - I, load % = I / ratingThe calculated current against the rating of the service or main breaker now. The IAEI house is 71.2 percent of a 200 A service with 57.7 A to spare, and 114 percent of a 125 A service, which is over.

Seven houses through the same formula

The first row is the IAEI Magazine example and the second is the Mike Holt example in EC&M, and the page gives the same totals. Rows with 1,800 sq ft show the same house with an air conditioner, a heat pump with and without a compressor lockout, and baseboard heat. In the last row, the IAEI house trades its air conditioner for a heat pump with strip heat.

General load, demand, heating and cooling, total, current and service size for seven houses
House	General load, VA	After demand, VA	Heat or cool, VA	Total, VA	Current, A	Service, A
2,900 sq ft, gas heat, EV charger and hot tub (IAEI example)	55,400	28,160	6,000	34,160	142.3	150
6,000 sq ft, 27,360 VA cooling, 17,100 W electric heat (Holt example)	140,096	62,038	27,360	89,398	372.5	400
1,800 sq ft, gas heat, 4,000 VA air conditioner	34,100	19,640	4,000	23,640	98.5	100
1,800 sq ft, 5,000 VA heat pump and 15,000 W strip heat	34,100	19,640	14,750	34,390	143.3	150
1,800 sq ft, same heat pump with the compressor locked out	34,100	19,640	9,750	29,390	122.5	125
1,800 sq ft, 20,000 W baseboard in 6 zones	34,100	19,640	8,000	27,640	115.2	125
2,900 sq ft IAEI house with a 5,000 VA heat pump and 15,000 W strip heat	55,400	28,160	14,750	42,910	178.8	200

Holt's article lists its dryer at 4,000 W in one place and 5,000 W in the sum, and the page takes his sum of 117,596 VA of fixed appliances as printed. His text says about 372 A and the page shows 372.5 A, because the page keeps the decimals of 62,038.4 VA. Both lead to 400 A.

Standards and data sources

NEC 2023, 220.82 (optional method, dwelling unit), 230.79(C) and Table 240.6(A) - the method, the size of the dwelling service and the standard ratings. NFPA's free viewer needs a login, so the text was read as IAEI and Mike Holt restate it, and the page says so.
IAEI Magazine, Christel Hunter, Residential Service Calculations in the National Electrical Code (May/June 2013) - the first worked example and the page default: 2,900 sq ft, a 6,000 VA air conditioner, range, dryer, hot tub, EV charger and water heater, 34,160 VA, 142 A and a 150 A service.
Mike Holt in EC&M, Dwelling Load Calculations Per the National Electrical Code (Jan 6, 2022, 2020 NEC) - the second worked example: 6,000 sq ft, 140,096 VA connected, 62,038 VA after demand, 27,360 VA of air conditioning against 11,115 W of heat, 89,398 VA, about 372 A and a 400 A service.
Mike Holt in EC&M, One-Family Dwelling Unit Load Calculations and Dwelling Unit Calculations - the wording of 220.82(A), (B) and (C)(1) through (6), the outside-dimensions rule for the area, the 8 kVA of 220.83 and the compressor that is left out when it cannot run with the supplemental heat. The second article is based on the 2008 NEC.
Mike Holt in EC&M, Services and the NEC, Part 2 of 2 (Feb 13, 2019) - 230.79(C): a one-family dwelling disconnect is rated at least 100 A, 3-wire, and the rating is never under the load found by Article 220.

Limitations of this calculator

This is a calculation of the load, not a load calculation accepted by a permit office. A licensed electrician or engineer prepares the calculation the local authority having jurisdiction (AHJ) and the utility ask for, and the service upgrade is installed under permit and inspection. Nothing here approves a panel.
220.82 is an alternative to the standard method of Article 220, Part III. The two methods give different numbers, and your AHJ may ask for a particular one. Run the standard method too before you sell a service upgrade or a heat pump on a number from this page.
The optional method is for one dwelling unit served by a single 120/240 V or 120/208 V 3-wire set of service or feeder conductors of 100 A or more. Multifamily buildings, three-phase and 4-wire services, and a dwelling fed by more than one set of conductors are outside this page.
The current is the total divided by 240 V, as both worked examples do. A 120/208 V dwelling service is allowed by 220.82, but no source we read shows its current, so the page works 120/240 V only.
The NEC text was read as IAEI and Mike Holt in EC&M print it, not in NFPA's own viewer. The paragraph letters of 220.82 differ between editions (the 2013 article numbers the general load differently from the 2020 and 2023 text), and one Holt article is based on the 2008 NEC. Check the edition your AHJ has adopted.
Enter nameplate VA or watts. For a motor, nameplate volts x amps. Appliances that plug into the general receptacles are already in the 3 VA per sq ft and the small-appliance circuits. The page adds only what you list as fastened in place or on its own circuit.
220.83, the method for loads added to an existing dwelling, is not worked. Mike Holt prints it with 8 kVA at 100 percent in place of 10 kVA, and with the larger of air conditioning and space heating. 220.87, the existing load from a year of maximum demand data at 125 percent, is not worked either. Ask the AHJ which section it accepts for a heat pump or an EV charger added to a house.
The page uses the 2023 numbering and text. The 2026 NEC moves Article 220 to Article 120 (Ryan Jackson in EC&M, July 15, 2026), so 220.82 is 120.82 there, and summaries of the 2026 edition report changed demand figures that were not checked against the code text for this page. Check the edition your AHJ has adopted.
The page does not size service conductors (Table 310.12), the neutral, the grounding electrode conductor or the panel bus, and it does not model load management systems, solar or batteries. It compares the calculated current only with the rating you enter for the service or main breaker.
The page works dwellings from 100 to 20,000 sq ft and refuses entries outside that range. Each load is limited to 200,000 VA.

Common mistakes with a service load

Adding every nameplate with no demand factor. The IAEI house has 55,400 VA of general load and a 6,000 VA air conditioner. Added straight, that is 61,400 VA, 255.8 A. The optional method gives 34,160 VA, 142.3 A. The first 10,000 VA counts in full and the rest at 40 percent, which is the reason the optional method is allowed only for a dwelling that fits 220.82.
Adding the air conditioner and the electric heat. 220.82(C) takes the larger of the cooling and the heating, not both. A 4,000 VA air conditioner and 10,000 W of electric heat on one thermostat count 6,500 VA, the heat at 65 percent, not 4,000 + 6,500 = 10,500 VA. Added together by mistake, the 1,800 sq ft house shows 125.6 A instead of 108.9 A.
Counting the garage and the porch in the square footage. The 3 VA per sq ft is for the outside dimensions of the dwelling without open porches, garages and spaces that cannot be finished later. A 600 sq ft garage left in adds 1,800 VA before demand. In the IAEI house that moves the service from 139.3 A to 142.3 A. It rarely changes the rating, but it can at the edge of a size.
Forgetting what the supplemental heat does to a heat pump. A 5,000 VA heat pump compressor with 15,000 W of strip heat counts the compressor in full plus 65 percent of the strip heat, 14,750 VA, unless the controls lock the compressor out while the strip heat runs. With the lockout the heating option counts only 65 percent of the strip heat, 9,750 VA (the compressor still counts in full as cooling, which here is smaller), and the 1,800 sq ft house drops from 143.3 A to 122.5 A. Take the lockout only if the controls are installed and documented.
Entering tons or BTU/h for the air conditioner. The load is the nameplate VA of the condenser and the air handler or furnace fan, rated volts x rated load amps. Tons and BTU/h are not electrical loads. Use the AC breaker size calculator for the circuit of one unit, and enter the nameplate VA here.
Reading the service size as the sum of the breakers. A panel full of 20 A breakers does not mean a large load, and a 200 A main does not mean the house draws 200 A. The service is sized from the calculated load. The IAEI house calculates to 142.3 A, 71.2 percent of a 200 A service, whatever the breaker count says.

Common questions about service load

How do I calculate the electrical service load of a house?

Under the NEC 220.82 optional method, add 3 VA per sq ft, 1,500 VA for each small-appliance and laundry circuit, and the nameplate of the fixed appliances. Take 100 percent of the first 10,000 VA and 40 percent of the rest, add the largest heating or air-conditioning load, and divide by 240 V. The IAEI example, 2,900 sq ft with a range, dryer, water heater, hot tub and EV charger, is 55,400 VA of general load, 28,160 VA after demand and 34,160 VA with the air conditioner, 142.3 A, a 150 A service.

Is 200 amps enough for my house?

For the IAEI house, 142.3 A is 71.2 percent of 200 A, with 57.7 A to spare, and a 150 A service is enough. A 6,000 sq ft house with 27,360 VA of cooling calculates to 372.5 A and needs 400 A. Enter your loads and your rating above. This is a calculation, not a measured demand, and the AHJ decides what it accepts.

Can my panel handle a heat pump?

Add the heat pump compressor and its supplemental heat to the loads you already have and compare the current with the rating. The IAEI house with a 5,000 VA compressor and 15,000 W of strip heat in place of the air conditioner calculates to 42,910 VA, 178.8 A. That is 89.4 percent of a 200 A service, 21.2 A to spare, and 28.8 A over a 150 A service. For an existing house the AHJ may ask for 220.83, which this page does not work.

How is supplemental electric heat counted for a heat pump?

220.82(C) takes 100 percent of the compressor plus 65 percent of the supplemental heat, and compares that with the other options. If the controls keep the compressor from running with the supplemental heat, the compressor is left out of that item, though it still counts in full as cooling under item (1). In the 1,800 sq ft example, a 5,000 VA compressor with 15,000 W of strip heat counts 14,750 VA, and 9,750 VA with the lockout.

What counts at 65 percent and what at 40 percent for electric heat?

Electric space heating counts 65 percent of the nameplate when it is fewer than four separately controlled units, and 40 percent for four or more. With 20,000 W of baseboard, three zones count 13,000 VA and six zones count 8,000 VA. Electric thermal storage and other heating that runs steadily counts 100 percent.

Does the 3 VA per square foot include the garage and the basement?

The area is the outside dimensions of the dwelling. Open porches, garages and spaces that cannot be finished later are left out, so a basement or attic that could be finished is normally counted. Ask the AHJ how it reads an unfinished space.

What is the smallest service for a house?

A one-family dwelling disconnect is rated at least 100 A, 3-wire (230.79(C)), and 220.82 applies only to services of 100 A or more. A small house with gas heat can calculate to less, for example 98.5 A for the 1,800 sq ft example with a 4,000 VA air conditioner, and the answer is still 100 A.

How is this different from the standard method?

Article 220, Part III is the standard method. It figures the loads one group at a time, each with its own demand factors. 220.82 is the optional method for one dwelling and can give a lower number. Your AHJ may ask for one of the two, so ask before you quote a service upgrade.

Does this work for a 120/208 volt service?

No. 220.82 allows a 120/208 V 3-wire dwelling service, but the worked examples we read all divide by 240 V, and none shows the current at 208 V. This page works 120/240 V only.

What if I am adding a load to an existing house?

220.83 is the section for added loads in an existing dwelling. Mike Holt prints its general load with 8 kVA at 100 percent in place of 10 kVA and the larger of air conditioning and space heating. This page does not work 220.83. 220.87 lets the existing load come from a year of the utility's maximum demand data instead: the highest demand at 125 percent plus the new load has to fit the service, as an EC&M Code Q&A works it on the 2011 text. Use this page as a first check, then ask the AHJ which section it accepts.

Does this replace a load calculation from an electrician?

No. The page gives preliminary numbers for estimating and for checking a quote. A licensed electrician prepares the calculation the permit office and the utility accept, and installs the service under permit and inspection.