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Electrical Panel Load Calculator (NEC Service Sizing)

Size a dwelling's electrical service by NEC Article 220's standard and optional methods, with the standard service rating that covers the one you choose.

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Which of the two NEC methods gives the headline figure — both are computed and both appear in the breakdown.

The standard calculation applies a separate demand factor to each class of load. The optional calculation lumps most of them together and takes the first 10 kVA at 100% and everything above it at 40%. On a typical house the optional method gives the smaller answer, which is why it exists; some inspectors expect one, some the other, and a service sized by the smaller of the two is only defensible if the jurisdiction accepts that method.

The edition your jurisdiction has adopted — adoption lags publication, often by years.

Of the figures this page uses, the one that moves between editions is electric-vehicle supply equipment: 220.57, which sets the EVSE load at the nameplate rating or 7,200 VA whichever is larger, arrived in the 2020 edition. Lighting, range and dryer demands are unchanged across all three. The 2023 edition renumbered much of Article 220 without changing those numbers.

The habitable floor area, measured to the outside of the exterior walls.

NEC 220.12 measures from the outside dimensions of the dwelling and excludes open porches, garages and unfinished or unused spaces unless they are adaptable for future use. An unfinished basement that could be finished counts; an attic with no floor does not.

The number of 20 A small-appliance circuits serving the kitchen, pantry and dining areas.

NEC 210.11(C)(1) requires at least two, which is why the field will not go below two. Larger kitchens and separate island or pantry circuits push the number higher; each one adds 1,500 VA to the calculation whether or not it is heavily loaded.

Whether the dwelling has the dedicated laundry receptacle circuit.

NEC 210.11(C)(2) requires one in a dwelling unit, so the usual answer is yes and it adds 1,500 VA. The exception is a unit with no laundry provision at all — some apartments in buildings with a shared laundry room.

The nameplate kilowatt rating of the electric range. Enter 0 for a gas range.

A single range of 12 kW or less has a demand of 8 kW under Table 220.55 Column C — the table already assumes you will never run every element at once. Above 12 kW the 8 kW figure rises 5% for each additional kilowatt. Separate wall ovens and counter-mounted cooktops on one circuit are treated as a single range of their combined rating.

The dryer's nameplate rating in volt-amperes. Enter 0 for a gas dryer or no dryer.

NEC 220.54 sets a floor of 5,000 VA, so anything you enter below that is raised to it. A typical electric dryer is 5,000 to 5,600 VA. A heat-pump dryer draws far less and still carries the 5,000 VA calculated load, because the rule is a minimum rather than a measurement.

Nameplate total for the water heater, dishwasher, disposal, microwave and similar fixed appliances.

Everything fastened in place except the range, the dryer, space heating and air conditioning, which are counted separately. A 4,500 W water heater, a 1,200 W dishwasher and a 900 W disposal come to 6,600 VA. Do not include portable appliances — they are already covered by the general lighting and receptacle load taken from the floor area.

The count of those appliances — four or more earns a demand factor, three or fewer do not.

NEC 220.53 allows 75% of the total nameplate where four or more fastened-in-place appliances are served, on the reasoning that they do not all run together. With three or fewer the full nameplate total is used, so the count genuinely changes the answer.

The larger of the electric heating load and the air-conditioning load — not both added together.

NEC 220.60 treats heating and cooling as noncoincident, so only the larger is included. For a heat pump, add the compressor to the supplemental resistance heat if they can run together. Enter 0 where heating is gas or oil and there is no air conditioning.

The charger's nameplate rating — 7,680 VA for a 32 A unit at 240 V. Enter 0 if none is planned.

Multiply the continuous amp rating by the voltage: a 32 A charger on 240 V is 7,680 VA, a 48 A one is 11,520 VA. Under the 2020 and 2023 editions the calculated load is that figure or 7,200 VA, whichever is larger, so a small charger does not reduce the calculation below 7,200. Where an energy management system limits the charger, a different and lower figure may be permitted — that is outside this page.

Calculated service load

155 A

Medium confidence

A screening calculation, not a load letter. Every figure here comes from the NEC's own demand tables, but a service upgrade is designed by a licensed electrician, permitted by the authority having jurisdiction and coordinated with the utility, whose own sizing rules and available capacity govern what can actually be installed.

Recommended service rating
175 A
Standard calculation (Part III)
154.69 A
Optional calculation (220.82)
116.67 A
Headline load in volt-amperes
37,125 VA
General lighting at 3 VA per sq ft
6,000 VA
Lighting group after Table 220.42 demand
5,625 VA
Range demand, Table 220.55 Column C
8,000 VA
Dryer, 5,000 VA minimum
5,000 VA
Fixed appliances at 75%
4,500 VA
EV supply equipment at 125%
9,000 VA
Then change the inputs to see how far the answer moves.

Show calculation logic

How this was calculated

Formula source(s)

  • NEC 220.12 and Table 220.12: dwelling general lighting and general-use receptacle load at 3 VA per square foot of floor area
  • NEC 220.52: 1,500 VA for each 2-wire small-appliance branch circuit and 1,500 VA for the laundry branch circuit
  • NEC Table 220.42: demand factors for lighting and receptacle loads — first 3,000 VA at 100%, 3,001 to 120,000 VA at 35%, remainder at 25%
  • NEC Table 220.55, Column C, Note 1: one household range of 12 kW or less has a demand of 8 kW, increased 5% per additional kW or major fraction above 12 kW
  • NEC 220.54: household clothes dryer at 5,000 VA or the nameplate rating, whichever is larger
  • NEC 220.53: four or more fastened-in-place appliances (other than ranges, dryers, space heating and air conditioning) may be taken at a 75% demand factor
  • NEC 220.60: noncoincident loads — where heating and cooling cannot operate together, only the larger is included
  • NEC 220.82: optional calculation for a dwelling on a 100 A or larger 120/240 V service — first 10 kVA of general load at 100%, remainder at 40%, plus the largest of the 220.82(C) heating and cooling figures
  • NEC 220.57 (2020 and 2023 editions): electric-vehicle supply equipment at the nameplate rating or 7,200 VA, whichever is larger. Under the 2017 edition the nameplate rating applies, treated as a continuous load under 625.41
  • NEC 240.6(A) standard overcurrent device ratings: 100, 125, 150, 175, 200, 225, 250, 300, 350, 400 A

Inputs used

Headline method
Standard calculation (Article 220, Part III)
NEC edition
NEC 2023
Dwelling floor area
2000 sq ft
Small-appliance branch circuits
2
Laundry branch circuit
Yes — dedicated laundry circuit
Range or cooktop nameplate (kW)
12
Clothes dryer nameplate (VA)
5000
Fastened-in-place appliances, total nameplate (VA)
6000
How many fastened-in-place appliances
4
Heating or cooling, whichever is larger (VA)
5000
EV supply equipment nameplate (VA)
7200

Intermediate steps

Recommended service rating
175 A
Standard calculation (Part III)
154.69 A
Optional calculation (220.82)
116.67 A
Headline load in volt-amperes
37,125 VA
General lighting at 3 VA per sq ft
6,000 VA
Lighting group after Table 220.42 demand
5,625 VA
Range demand, Table 220.55 Column C
8,000 VA
Dryer, 5,000 VA minimum
5,000 VA
Fixed appliances at 75%
4,500 VA
EV supply equipment at 125%
9,000 VA
Final result154.69 A

Confidence note: A screening calculation, not a load letter. Every figure here comes from the NEC's own demand tables, but a service upgrade is designed by a licensed electrician, permitted by the authority having jurisdiction and coordinated with the utility, whose own sizing rules and available capacity govern what can actually be installed.

What this calculation does not cover

  • This is a screening calculation and not a submitted load letter. A service change needs a licensed electrician, a permit from the authority having jurisdiction, and the utility's agreement — the utility's transformer, service drop and metering all have their own limits, and none of them appears in Article 220.
  • The 125% continuous-load multiplier on the EV charger follows 230.42(A) for service conductors. Some authorities read 220.57's 7,200 VA as already being the calculated load and do not apply 125% on top of it, which changes the answer by a quarter of the charger's load — worth establishing locally before sizing anything.
  • 220.82(C) is only partly modelled. The optional calculation here takes the heating or cooling figure you entered at 100%, which is correct for air conditioning and for a heat pump with its supplemental heat. The reduced percentages the code allows — 65% for central systems with supplementary heat, 65% for fewer than four separately controlled electric space heating units, 40% for four or more — need a description of the heating system this page does not ask for, and they would lower the result.
  • The Canadian Electrical Code is not this calculation. CEC Section 8 sizes a single-dwelling service from a minimum figure per unit of floor area with its own demand factors, and it produces materially different answers from NEC Article 220. Nothing on this page has been checked against the CEC, and it must not be used for Canadian permit work.
  • Conductor sizing is a separate step. NEC 310.12 permits the ungrounded service conductors of a 120/240 V single-phase dwelling service to be sized at 83% of the service rating, and conductor ampacity is then subject to temperature and conduit-fill corrections. The recommended rating above is the overcurrent device, not the wire.
  • Load management and demand-controlled equipment are outside the model. Where an energy management system limits an EV charger or a heat pump, the code permits a lower calculated load, and a house that would otherwise need a service upgrade may not. That determination belongs with the system's listing and the designer.

Add the equipment this sizes

This result is a specification — 155 A — not a quantity. Put the thing it sizes into your project: how many, what you call it, and your supplier’s price.

Part of a bigger job

This trade is one line of a job takeoff. Run the whole job and every other trade comes back with it, off the same measurements.

Computed in your browser — nothing you enter is uploaded. Presented in US customary units and US trade terminology. Where a formula follows a published standard, that standard and its edition are cited beside it on this page; where none governs, the page says so. Local amendments override model codes — verify against the code in force where you build.

Sources checked 2026-09-11 · v1.0.0

Regulatory standards & verification citations10
  1. NEC 220.12 and Table 220.12: dwelling general lighting and general-use receptacle load at 3 VA per square foot of floor area
  2. NEC 220.52: 1,500 VA for each 2-wire small-appliance branch circuit and 1,500 VA for the laundry branch circuit
  3. NEC Table 220.42: demand factors for lighting and receptacle loads — first 3,000 VA at 100%, 3,001 to 120,000 VA at 35%, remainder at 25%
  4. NEC Table 220.55, Column C, Note 1: one household range of 12 kW or less has a demand of 8 kW, increased 5% per additional kW or major fraction above 12 kW
  5. NEC 220.54: household clothes dryer at 5,000 VA or the nameplate rating, whichever is larger
  6. NEC 220.53: four or more fastened-in-place appliances (other than ranges, dryers, space heating and air conditioning) may be taken at a 75% demand factor
  7. NEC 220.60: noncoincident loads — where heating and cooling cannot operate together, only the larger is included
  8. NEC 220.82: optional calculation for a dwelling on a 100 A or larger 120/240 V service — first 10 kVA of general load at 100%, remainder at 40%, plus the largest of the 220.82(C) heating and cooling figures
  9. NEC 220.57 (2020 and 2023 editions): electric-vehicle supply equipment at the nameplate rating or 7,200 VA, whichever is larger. Under the 2017 edition the nameplate rating applies, treated as a continuous load under 625.41
  10. NEC 240.6(A) standard overcurrent device ratings: 100, 125, 150, 175, 200, 225, 250, 300, 350, 400 A

Which documents these citations point at

  • National Electrical Code (NFPA 70) — 220.12, 220.52, Table 220.42, Table 220.55, 220.54, 220.53, 220.60, 220.82, 220.57, 240.6(A) (United States)Electrical installations — conductor sizing and protection, load calculation, wiring methods, grounding and working clearances.

A code or standard has force only where a jurisdiction has adopted it, usually with local amendments. This site holds no adoption data for any authority, so check what is in force with the authority where you build. Any section cited above without an edition should be checked against the edition in force where you build. What it would take to know.

Cite this page

Your workspace

Most jobs need more than one number. Add the calculators you need next and they open right here, underneath this one — your figures stay on screen and nothing is lost to a page change.

Called something else where you work? Consumer unit / breaker panel — the term in each market, how close the equivalence really is, and the standard that governs it.

Still deciding? EV Charger: Service Upgrade vs Load Management — the factors that actually differ, with no invented prices.

Worked example: Electric vehicle charger circuit — step 2 of 9

Already gone wrong? A breaker keeps tripping

How to calculate electrical panel load (NEC service sizing) in 12 steps

  1. Headline methodWhich of the two NEC methods gives the headline figure — both are computed and both appear in the breakdown.
  2. NEC editionThe edition your jurisdiction has adopted — adoption lags publication, often by years.
  3. Dwelling floor areaThe habitable floor area, measured to the outside of the exterior walls.
  4. Small-appliance branch circuitsThe number of 20 A small-appliance circuits serving the kitchen, pantry and dining areas.
  5. Laundry branch circuitWhether the dwelling has the dedicated laundry receptacle circuit.
  6. Range or cooktop nameplate (kW)The nameplate kilowatt rating of the electric range. Enter 0 for a gas range.
  7. Clothes dryer nameplate (VA)The dryer's nameplate rating in volt-amperes. Enter 0 for a gas dryer or no dryer.
  8. Fastened-in-place appliances, total nameplate (VA)Nameplate total for the water heater, dishwasher, disposal, microwave and similar fixed appliances.
  9. How many fastened-in-place appliancesThe count of those appliances — four or more earns a demand factor, three or fewer do not.
  10. Heating or cooling, whichever is larger (VA)The larger of the electric heating load and the air-conditioning load — not both added together.
  11. EV supply equipment nameplate (VA)The charger's nameplate rating — 7,680 VA for a 32 A unit at 240 V. Enter 0 if none is planned.
  12. Calculated service loadThe tool computes the calculated service load from those figures and shows the formula, its sources, and a confidence rating alongside it.

Calculated service load by dwelling floor area

Page defaults, not your figures above.

Dwelling floor areaCalculated service load (A)
1,000 sq ft150
1,500 sq ft153
2,000 sq ft155
2,500 sq ft157
3,000 sq ft159
3,500 sq ft161
4,000 sq ft163

Frequently asked questions

Why do the two methods give different answers?
Because they model diversity differently. The standard calculation applies a specific demand factor to each class of load — 35% to most of the lighting group, 75% to four or more fixed appliances, a table for the range. The optional calculation abandons that detail and takes the first 10 kVA of nearly everything at 100% and the rest at 40%. On a house with a lot of connected load the flat 40% is more generous, which is why the optional method usually produces the smaller service. Both are in the code; neither is a shortcut.
Which method will my inspector expect?
The one your authority having jurisdiction accepts, so ask before you size anything: where 220.82 applies, most electricians use it because it is less work and gives the smaller number. Section 220.82 is available for a dwelling served by a single 120/240 V or 208Y/120 V set of service conductors rated 100 A or more. Some authorities having jurisdiction want the standard calculation on a service change, particularly where the result is close to the existing rating. A service sized on the smaller of two legitimate answers is only defensible if the jurisdiction accepts that answer.
Why is a 12 kW range only counted as 8 kW?
Because Table 220.55 has already done the diversity for you. A range has several elements and an oven, and the nameplate is the sum of all of them running at once, which does not happen — and even if it did, it would not happen for long enough to matter to a service conductor. Column C encodes that as a flat 8 kW demand for a single range up to 12 kW. Above 12 kW the figure climbs 5% per additional kilowatt.
Does the EV charger really have to be 7,200 VA?
Under the 2020 and 2023 editions, 220.57 sets the calculated load at the nameplate rating or 7,200 VA, whichever is larger, so a small charger does not buy a smaller calculation. The 2017 edition has no such section and the nameplate governs. There is a genuine route around it: where a listed energy management system limits what the charger can draw, the code allows the calculation to reflect that limit — and on a house sitting just over a service rating, that is often cheaper than an upgrade.
Can I use this in Canada?
No. The Canadian Electrical Code sizes a single-dwelling service under Section 8 with its own minimum figures and its own demand factors, and it is not a variation on Article 220 — it reaches materially different numbers on the same house. This page implements the NEC only, nothing here has been checked against the CEC, and it should not be used for Canadian permit work.
My calculated load is just under my existing service. Am I fine?
The calculation says the service is adequate for the loads you entered, which is not the same as saying the panel is. Physical space for breakers, the busbar rating, the age and condition of the equipment, the number of available circuits and whether the panel is a type still considered serviceable are all separate questions, and any one of them can force a replacement on a service that calculates comfortably.
Why does the recommendation skip 320 A?
Because 320 A is not an overcurrent device rating. It is a utility meter-socket classification — a 320 A class base is rated for 320 A continuous and 400 A intermittent, and the overcurrent device behind it is a 400 A one. The list here is the standard device ratings of 240.6(A), which is what actually protects the service.
Preliminary estimate, not certified engineering. This tool produces an indicative quantity calculation for planning purposes only — it is not a certified structural analysis, a guaranteed material takeoff, or a substitute for building department approval. Always verify measurements on-site and have a licensed contractor or structural engineer review any load-bearing, code-sensitive, or safety-critical work before purchasing materials or starting construction. Spotted an arithmetic or standards error? Report it to contact@craftquantities.com with your inputs — a confirmed fix gets a permanent check of its own, so the same mistake cannot come back.