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Load Calculator
NEC 2023 Article 220 Part III — every load gets its own demand factor.
Electrical Load Calculator
Size a residential service the way the inspector checks it — enter habitable floor area and appliance nameplates, pick the NEC standard or optional method, and get the calculated load in amps, the recommended service size, spare capacity, and a demand breakdown citing every article applied. Free, no signup.
Free
Cooking, heat pump & extra appliances
Everything the NEC lets you treat separately — extra cooking units, heat pump strips, additional fastened appliances, and the largest-motor adder.
Calculated load
123.8 A
29,700 VA ÷ 240 V single-phase
Tight — little room to grow
Recommended service125 A
Your service load at a glance
Calculated load
123.8 A29,700 VA after all demand factors
Total connected load
40,600 VA169.2 A if everything ran at once
Demand-adjusted load
29,700 VA73.2% of connected load
Recommended service
125 ANext standard residential rating (NEC 240.6(A), 100 A floor per 230.79(C))
Spare capacity
1.0%300 VA left for future loads
Heating vs cooling
5,000 VAAir conditioning — NEC 220.60
Demand breakdown, line by line
Every load with the NEC article it comes from and the demand factor applied. Rows showing “—” roll into the subtotal beneath them.
| Load | Connected | Demand factor | Demand |
|---|---|---|---|
| General lighting & general-use receptaclesNEC 220.41 | 6,000 | 3 VA/ft² | — |
| Small-appliance branch circuits (2)NEC 220.52(A) | 3,000 | 1,500 VA each | — |
| Laundry branch circuits (1)NEC 220.52(B) | 1,500 | 1,500 VA each | — |
| Lighting & receptacle demandNEC Table 220.45 | 10,500 | First 3,000 VA @ 100% + 7,500 VA @ 35% | 5,625 |
| Cooking appliances (1)NEC Table 220.55 | 12,000 | Column C · 8 kW for 1 appliance | 8,000 |
| Electric clothes dryerNEC 220.54 | 5,000 | 100% of nameplate | 5,000 |
| Fastened-in-place appliances (4)NEC 220.53 | 8,100 | 75% — four or more | 6,075 |
| Air conditioningNEC 220.60 | 5,000 | 100% — larger of heat vs cool | 5,000 |
Industry benchmarks
- Gas heat / gas water heat, no EV60–90 AUsually lands on a 100 A service — the NEC 230.79(C) floor.
- All-electric, no EV90–150 ARange + dryer + water heater + heat typically needs 150–200 A.
- All-electric + Level 2 EV charger150–250 AA 48 A EVSE alone adds 14.4 kVA — this is the usual 200 A upgrade trigger.
Built on the 2023 NEC (NFPA 70). Section numbers moved in that edition — general lighting is now 220.41 and the lighting demand table is Table 220.45. Your AHJ has the final say on the method and the numbers.
What you'll get
Enter the dwelling and its appliances
Habitable floor area drives the 3 VA/ft² general lighting load. Add the range, dryer, water heater, dishwasher, disposal, microwave, air conditioning, electric heat, and EV charger nameplates — extra cooking units, heat pump strips, and additional fastened appliances live in the advanced section.
Choose the standard or optional method
The standard method (NEC 220 Part III) applies a separate demand factor to every load group. The optional method (NEC 220.82) takes the first 10 kVA at 100% and the remainder at 40%, then adds the largest of the six heating and air-conditioning selections. Toggle between them and compare.
Read the load, the service size, and the breakdown
Get the calculated load in amps, total connected VA, demand-adjusted VA, the next standard service rating (100/125/150/200/225/300/400 A), spare capacity percentage, and a line-by-line table showing each load, its NEC article, and the demand factor applied.
How it works
- 1
Enter the dwelling and its appliances
Habitable floor area drives the 3 VA/ft² general lighting load. Add the range, dryer, water heater, dishwasher, disposal, microwave, air conditioning, electric heat, and EV charger nameplates — extra cooking units, heat pump strips, and additional fastened appliances live in the advanced section.
- 2
Choose the standard or optional method
The standard method (NEC 220 Part III) applies a separate demand factor to every load group. The optional method (NEC 220.82) takes the first 10 kVA at 100% and the remainder at 40%, then adds the largest of the six heating and air-conditioning selections. Toggle between them and compare.
- 3
Read the load, the service size, and the breakdown
Get the calculated load in amps, total connected VA, demand-adjusted VA, the next standard service rating (100/125/150/200/225/300/400 A), spare capacity percentage, and a line-by-line table showing each load, its NEC article, and the demand factor applied.
How NEC Article 220 turns nameplates into a service size
A dwelling never runs every appliance at once, so the NEC lets you discount the connected load before sizing the service. The standard method in Article 220 Part III does it load by load: general lighting and receptacles at 3 VA per square foot (220.41) plus two small-appliance circuits and a laundry circuit at 1,500 VA each (220.52), all pushed through the Table 220.45 tiers — first 3,000 VA at 100%, 3,001 to 120,000 VA at 35%, the remainder at 25%. Cooking equipment gets Table 220.55, which cuts a 12 kW range to an 8 kW demand load. Four or more fastened-in-place appliances drop to 75% (220.53), a dryer is the larger of 5,000 VA or nameplate (220.54), and only the larger of heating or air conditioning is carried because they are noncoincident (220.60).
The optional method in 220.82 trades precision for speed: pool the general loads and every appliance nameplate, take the first 10 kVA at 100% and everything above it at 40%, then add the largest of six heating and cooling selections — 100% of the air conditioning, 100% of a heat pump, a heat pump compressor plus 65% of supplemental strips, or resistance heat at 65% (fewer than four separately controlled zones) or 40% (four or more). It is only permitted on a 120/240 V or 208Y/120 V three-wire service rated 100 A or greater. Either method ends the same way: divide the calculated volt-amperes by 240, round up to the next standard rating, and confirm the 100 A minimum in 230.79(C). This calculator implements the 2023 edition of both methods and shows every article it applied, so you can hand the breakdown to a plan reviewer.
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View statesLoad Calculator FAQs
Which NEC edition and articles does this calculator implement?
The 2023 NEC (NFPA 70). Article 220 was reorganised in 2023, so the section numbers differ from earlier editions — general lighting moved from 220.12 to 220.41 and the lighting demand table moved from Table 220.42 to Table 220.45. The calculator also uses 220.51, 220.52, 220.53, 220.54, Table 220.55, 220.57 (the new EVSE load), 220.60, 220.82, 230.79(C), and 240.6(A). Demand factor values themselves are unchanged from the 2017 and 2020 editions, so results match older worksheets. This is a design aid — the authority having jurisdiction always governs the method, the numbers, and the final service size.
Should I use the standard method or the optional method?
The optional method (220.82) is faster and usually returns a smaller service for a typical all-electric home, which is why most residential plan sets use it. The standard method (220 Part III) is always permitted, some jurisdictions require it, and it is the one that matches how an inspector checks an existing panel load by load. Run both — the toggle keeps every input, so you can see the difference in seconds and submit whichever is more favourable.
Why is a 12 kW range only an 8,000 VA load?
NEC Table 220.55 Column C caps the demand for a single household cooking appliance rated not over 12 kW at 8 kW, because a range never draws full nameplate on every element at once. Over 12 kW, Note 1 raises that 8 kW by 5% for each additional kilowatt or major fraction over 12 — a 16.6 kW range is 4.6 kW over, which rounds to 5, so the demand is 8 kW × 1.25 = 10 kW. Cooktops and wall ovens rated 1¾ to 8¾ kW may instead use Note 3 with the Column A and Column B percentages, which is usually lower.
How is an EV charger counted in the load calculation?
NEC 220.57, new in the 2023 edition, sets the EVSE load at 7,200 VA or the nameplate rating, whichever is larger — a 48 A Level 2 charger is 11,520 VA. The 2023 NEC also bars EVSE from the 220.53 75% fastened-appliance demand factor. This calculator adds the EVSE at 100% after the demand factors in both methods and applies the 125% continuous multiplier from 230.42(A)(1) and 625.41, which is the conservative reading and matches how the 2026 edition settles the optional method.
