Service & Load Calculator
Estimate the service size for a dwelling using the NEC Article 220 standard method. Enter living area and the major loads — small-appliance and laundry circuits, fixed appliances, range, dryer, and the larger of heat or AC — to get the calculated load in VA and amps, the recommended standard service size, and a printable line-item calc sheet.
Dwelling Loads
Calculated Service
Simplified NEC Article 220 standard method (dwelling). Lighting demand: first 3000 VA @ 100%, remainder @ 35%. Verify against a full load calc for permit.
Service Load Calculation — Dwelling
NEC Article 220 standard method (simplified) — prepared with the NORDIX Service Load Calculator (nordixhq.com/tools/service-load-calculator)
| Line item | Connected VA | Demand VA |
|---|---|---|
| General lighting — 2,000 ft² × 3 VA/ft² | 6,000 | |
| Small-appliance circuits — 2 × 1,500 VA | 3,000 | |
| Laundry circuits — 1 × 1,500 VA | 1,500 | |
| Subtotal — general lighting & receptacle load | 10,500 | |
| First 3,000 VA @ 100% (220.42) | 3,000 | 3,000 |
| Remainder @ 35% (220.42) | 7,500 | 2,625 |
| Net general lighting demand | 5,625 | |
| Fixed appliances — 4 fastened in place @ 75% (220.53) | 6,000 | 4,500 |
| Range / cooking equipment (demand-adjusted entry) | 8,000 | 8,000 |
| Dryer (220.54) | 5,000 | 5,000 |
| Heat or A/C — larger of the two (220.60) | 10,000 | 10,000 |
| Total calculated load | 33,125 VA |
| Calculated amperes @ 240 V | 138 A |
| Recommended service size | 150 A |
Method: simplified NEC Article 220 standard method for a one-family dwelling — general lighting at 3 VA/ft², small-appliance and laundry circuits at 1,500 VA each, lighting demand per 220.42 (first 3,000 VA @ 100%, remainder @ 35%), fastened-in-place appliances at 75% when four or more (220.53), dryer per 220.54, and the larger of heating vs air-conditioning per 220.60. Range/cooking VA is taken as entered (apply Table 220.55 demand before entry). Service size is the next standard rating at or above the calculated amperes. Verify against a full Article 220 calculation for permit — the AHJ governs.
How this calculator works
The Article 220 standard method builds the service load as a chain of demand factors — the code’s recognition that not everything in a house runs at once. The general lighting load (3 VA/ft²) plus the small-appliance and laundry circuits take the 220.42 lighting demand; fixed appliances take the 220.53 factor; and heat vs AC resolves to whichever is larger (220.60):
total VA = demand(lighting + SA + laundry) + fixed appl. (×0.75 if ≥4) + range + dryer + max(heat, AC)
amps = total VA ÷ service voltage · service = next standard size up
The range entry is taken as already demand-adjusted — a 12 kW household range enters at its Table 220.55 demand (typically 8 kVA), not nameplate. The recommended service is the next standard rating at or above the calculated amps, from the 100 / 125 / 150 / 200 / 225 / 300 / 400 A ladder.
Worked example
A 2,000 ft² dwelling with two small-appliance circuits, one laundry circuit, four fixed appliances totaling 6,000 VA, an 8 kVA range (demand-adjusted), a 5,000 VA dryer, and 10 kVA of heat (larger than the AC), at 240 V — the calculator’s defaults:
- General load: 2,000 × 3 + 2 × 1,500 + 1 × 1,500 = 10,500 VA.
- 220.42 demand: 3,000 @ 100% + 7,500 × 0.35 = 3,000 + 2,625 = 5,625 VA.
- Fixed appliances (four → 75%): 6,000 × 0.75 = 4,500 VA.
- Total: 5,625 + 4,500 + 8,000 + 5,000 + 10,000 = 33,125 VA.
- 33,125 ÷ 240 = 138.0 A → next standard service: 150 A.
The printable calc sheet lays out these exact line items — connected VA and demand VA per row — in the format plan reviewers expect.
Reference: the demand factors applied
Each load in the standard method and how the calculator treats it:
| Load | Treatment | NEC reference |
|---|---|---|
| General lighting & receptacles | 3 VA per ft² of living area | Art. 220 std. method |
| Small-appliance circuits | 1,500 VA each (minimum two) | Art. 220 std. method |
| Laundry circuit | 1,500 VA each | Art. 220 std. method |
| Lighting demand factor | First 3,000 VA @ 100%, remainder @ 35% | 220.42 |
| Fastened-in-place appliances | 75% of nameplate sum when 4 or more; else 100% | 220.53 |
| Range / cooking equipment | Entered demand-adjusted (apply the range demand table first) | Table 220.55 |
| Clothes dryer | Nameplate, 5,000 VA minimum | 220.54 |
| Heating vs air conditioning | The larger of the two only (noncoincident) | 220.60 |
Frequently asked questions
What size electrical service does a 2,000 square foot house need?
Run the numbers, not the folklore — but here's the shape of it. Under the standard method, 2,000 ft² of general lighting (6,000 VA) plus two small-appliance and one laundry circuit, a typical range, dryer, 6 kVA of fixed appliances, and 10 kVA of heat works out to roughly 33 kVA, about 138 A at 240 V — so a 150 A service calculates, and most builders install 200 A for headroom and future EV or heat-pump load. Change the heat or add a car charger and the answer moves, which is exactly what this calculator is for.
What is the difference between the standard and optional load calculation methods?
This tool uses the NEC Article 220 standard method: each load category gets its own demand factor and everything is summed. The optional method (NEC 220.82, for dwellings served at 100 A or more) instead takes the first 10 kVA of general load at 100% and the remainder at 40%, plus the HVAC at its own factors — it usually produces a smaller calculated load for the same house. Both are legal for dwellings; use whichever the design calls for and verify against the code edition adopted in your jurisdiction.
Do I add both heating and air conditioning to the load calc?
No — enter only the larger of the two. NEC 220.60 lets noncoincident loads, ones that can't run at the same time, be counted once at the largest value, and heating versus cooling is the classic case. Electric resistance heat almost always wins over the AC; with a heat pump plus supplemental strip heat, count what can actually operate together.
Why does only 35% of the lighting load count?
Diversity. The general-lighting demand factor — first 3,000 VA at 100%, the remainder at 35% for dwellings — reflects that nobody runs every light and every receptacle at once, and the NEC lets the service be sized for realistic peak demand rather than the connected total. The small-appliance and laundry circuits (1,500 VA each) get rolled into that same demand calculation. Verify the demand tables against the NEC edition in force in your jurisdiction.
What number do I enter for the range?
The demand-adjusted VA, not the nameplate. Household cooking equipment gets big demand factors from NEC Table 220.55 — one range rated 12 kW or less counts as 8 kW (Column C), which is why this calculator defaults to 8,000 VA. Enter the nameplate only if you intend to skip the demand factor and be deliberately conservative.
Is a 100 A service still allowed?
Yes. NEC 230.79(C) sets 100 A as the minimum service disconnect rating for a one-family dwelling, and a small all-gas house can genuinely calculate under it. The practical caution is headroom: electrification — EV charging, heat pumps, induction ranges — eats a 100 A service quickly, so most new work and heavy-up projects go straight to 200 A. Verify against the code edition adopted in your jurisdiction.
Method: simplified NEC Article 220 standard method for a one-family dwelling — general lighting at 3 VA/ft², small-appliance and laundry circuits at 1,500 VA each, lighting demand per 220.42, fastened-in-place appliances per 220.53, dryer per 220.54, range VA taken as entered (apply Table 220.55 demand before entry), and the larger of heating vs air-conditioning per 220.60. The optional method (220.82) and multi-family, motor, and continuous-load refinements are not modeled. This is a planning estimate — run a full, stamped Article 220 calculation for permit; the AHJ governs.
The service size drives the grounding system — see the grounding electrode conductor chart and bonding jumper size chart, both keyed to the service conductors. Pair with the Wire Ampacity Calculator for the service and feeder conductors and the Generator Sizing Calculator if the dwelling gets standby power.