Residential use only: For residential electrical load calculations only — NEC Article 220. Not for commercial or multi-family use.
MIT License: This tool is provided AS-IS, without warranty of any kind. You are solely responsible for all calculations and compliance with your local code. Use at your own risk.
MIT License: This tool is provided AS-IS, without warranty of any kind. You are solely responsible for all calculations and compliance with your local code. Use at your own risk.
Project Information
Auto-detected from state selection. Change only if your AHJ uses a different adoption.
Code adoption varies by AHJ. Always verify the applicable edition with your local building department. Auto-detection is based on state-level adoption data as of May 2026 and may not reflect local amendments.
Building & Service Parameters
General lighting = sq ft × 3 VA (NEC Tbl 220.12)
NEC 210.11(C)(1)
NEC 210.11(C)(2)
Calculation Method
Fixed Appliances
Set Qty to 0 to exclude an appliance, or 1+ to include it. Rating (VA) and voltage are pre-filled with typical values — adjust to match nameplate data.
Description
VA
Voltage
Qty
Demand Factor
Note
HVAC Loads
Only the largest heating or cooling load is counted per NEC 220.60. Set qty to 0 to exclude. No electric HVAC? Leave all quantities at 0 — the section is excluded from the calculation.
Description
VA
Voltage
Qty
Demand Factor
Note
Special Loads
EV chargers, spas, pools, and other special loads use individual demand factors. Solar PV produces a negative offset reducing the total. Set qty to 0 to exclude.
Description
VA
Voltage
Qty
Demand Factor
Note
Custom Loads
Add any load not covered above. Enter description, VA rating, voltage, quantity, and a demand factor (1.0 = full load; enter 0.75 for 75%, etc.).
Description
VA
Voltage
Qty
Demand Factor
Note
📋
Complete inputs and click Calculate Load to generate the report.
Panel Configuration
Circuit Schedule
| # | Type | Description — Left Bus | A | VA | # | Type | Description — Right Bus | A | VA |
|---|
This guide answers the practical question: "what do I actually type into the calculator?"
1. Quick Reference — Terms & When to Use Them
| Term | Definition | Use in calculator? |
|---|---|---|
| Gross / outside sq ft | Measured from exterior wall surfaces, per floor, summed across floors. Excludes garages, unfinished basements, open porches. | ✅ Use this — it's what NEC 220.12 wants. Round up slightly when uncertain. ❌ Don't include garages, unfinished basements, or open porches. |
| Living / listing sq ft | Interior finished space only (what real estate listings quote) | ❌ Don't use directly — usually smaller than gross |
| Nominal Voltage System — 120/240V | Standard single-phase residential service | ✅ Default for virtually all single-family homes, townhouses, and duplexes on a typical utility transformer drop |
| Nominal Voltage System — 120/208V | Appears when a dwelling unit is fed from a 3-phase building service | ✅ Use only for an individual unit in a multi-family building with 3-phase service (apartments/condos). If unsure, it's 240V. |
| Optional Method (NEC 220.82) | Simpler, fewer steps, generally a smaller calculated load than Standard Method | ✅ Default choice — new construction or existing home, no special circumstances |
| Standard Method (NEC 220.40+) | Granular, item-by-item demand factors | ✅ Use when Optional Method doesn't qualify, or AHJ requires line-item detail (common for additions/partial renovations) |
| Measured Load Method (NEC 220.87) | Uses 12 months of actual utility/AMI demand data instead of theoretical worst-case loads | ✅ Existing homes only, when you have utility data and want to avoid an oversized service upgrade |
| Small Appliance Circuits | A dedicated 20A, 120V circuit serving only receptacles in the kitchen, pantry, breakfast room, or dining room — no lighting, no other rooms | ✅ Count dedicated circuits, not appliances or outlets. Minimum 2; larger kitchens sometimes 3. ❌ Don't total up wattage of what's plugged in — NEC already assumes 1,500 VA/circuit. |
| Laundry Circuits | A dedicated 20A, 120V circuit serving the laundry area's receptacle(s) — typically the washer and/or a gas dryer's 120V plug | ✅ Count dedicated circuits only. ❌ The 240V electric dryer outlet is never part of this count — that goes in Fixed Appliances. |
2. Quick Decision Table — "Where Does X Go?"
| If it's... | Goes in... |
|---|---|
| General lighting, any room | Nowhere — sq ft × 3 VA covers it |
| Bedroom / hallway / bathroom receptacles | Nowhere — sq ft × 3 VA covers it |
| Kitchen/dining countertop receptacle circuit | Small Appliance Circuits count |
| Toaster, blender, coffee maker, mixer (plugged into a SA circuit) | Nowhere extra — already covered by the SA circuit's 1,500 VA allowance |
| Refrigerator | ⚠️ Depends on local AHJ — often its own dedicated circuit, not an SA circuit. If dedicated, treat as Custom Loads (nameplate VA) or per local rule; verify before defaulting to SA count |
| Washer's 120V receptacle | Laundry Circuits count |
| Gas dryer's 120V plug (motor/controls/igniter) | Laundry Circuits count — same circuit as washer keeps count at 1; separate dedicated 120V breaker bumps it to 2 |
| Second laundry area / utility sink, own dedicated circuit | Laundry Circuits count, +1 |
| Electric dryer (240V) | Fixed Appliances → Dryer |
| Electric range / cooktop / wall oven | Fixed Appliances → respective row, nameplate VA |
| Gas range / gas wall oven | Fixed Appliances → respective row — use the unit's electrical nameplate (igniter/controls only, typically 200–600 VA), not the gas BTU rating. If nameplate isn't available, qty = 0 with a note explaining the omission is acceptable given the small magnitude |
| Dishwasher, disposal, built-in microwave | Fixed Appliances → respective row |
| Water heater (electric) | Fixed Appliances → Water Heater |
| A/C, heat pump, furnace blower, strip heat | HVAC Loads (largest load counted automatically per NEC 220.60) |
| EV charger, hot tub, pool pump, sauna, solar PV, battery storage, workshop subpanel | Special Loads |
| Garage lighting/receptacles (typical — a few fixtures, 1–2 GFCI outlets) | Custom Loads — small flat entry, ~500–800 VA, qty 1, DF 1.0 |
| Garage with EV charger, workshop equipment, or a freezer | Special Loads (EV/Workshop) or Custom Loads (freezer) — not the flat garage allowance above |
| GFCI/AFCI-protected circuit | Nowhere extra — it's still whatever category it normally is. Note "GFCI"/"AFCI" in the description field for documentation only |
| Low-voltage security / doorbell / thermostat | Nowhere — immaterial (typically <50 VA), skip |
| Installed-but-unused circuit (e.g. spare 240V dryer outlet, gas dryer in service) | qty = 0, with a note documenting why it's unused |
| Anything unusual not covered above | Custom Loads, with nameplate VA and a note explaining what it is |
HVAC equipment — finding the right VA value
| Equipment | Where to find VA | Notes |
|---|---|---|
| A/C condenser / compressor | Nameplate RLA (Rated Load Amps) × volts | Don't use MCA — it already includes a safety margin; using it double-counts |
| Heat pump (heating mode) | Same as A/C — nameplate RLA × volts | Aux/strip heat is a separate row |
| Gas furnace, electric blower | Nameplate blower motor FLA × 120V | Almost all gas furnaces have one — typically 540–1,020 VA |
| Pure gas heat, no electric blower (rare) | N/A | qty = 0, nothing to enter |
| Electric resistance heat / strip heat | Nameplate kW of elements | kW ≈ VA since resistive, PF ≈ 1 |
| System has no match (e.g. gas furnace + no separate A/C) | — | Leave unused rows at qty = 0; the HVAC section is excluded entirely if all rows are 0 |
3. Solar PV and Battery Storage
How these are treated:
- Solar PV (NEC 220.5 / 705): Modeled as a load offset — enter the inverter's continuous output rating (not panel STC wattage) and the calculator applies a −100% demand factor, subtracting it from total calculated load. This reflects on-site generation reducing net service demand. Caveat: this is simplified for load-calc purposes only — actual interconnection compliance (705.12 load-side/supply-side taps, the 120% busbar rule) is a separate review, not handled by this offset.
- Battery Storage (NEC 706): Modeled as a standard +100% load — the charging circuit draws from the panel regardless of how the battery is later used. Enter the charger's nameplate input rating, not the battery's kWh capacity.
- Both together: Enter both. Solar nets out load; battery still adds its charging draw. Don't assume the pairing nets to zero — the battery's charging circuit pulls from the panel independently of solar production timing.
4. Custom Loads — Determining the Demand Factor
There's no NEC table for miscellaneous/custom loads, so this is an engineering judgment call:
- Default to 1.0 (100%) — conservative and defensible; most AHJs accept it without question.
- Use below 1.0 only with justification — e.g. a cyclical load that never runs simultaneously with other major loads, or a citable NEC article (motors under Article 430 have their own demand provisions).
- Never guess low just to shrink the total — NEC demand factors reflect codified diversity assumptions, not personal estimates of duty cycle.
- Document any non-1.0 value in the Note field — e.g. "Continuous-duty motor, Art. 430.22 — 125% applied" or "Intermittent sump pump, per local AHJ allowance." This is the first thing a reviewer will question.
Rule of thumb: if in doubt, use 1.0. It's always defensible; anything lower needs a citation.
5. General Do's and Don'ts
Do:
- Use nameplate/data-plate values wherever a specific appliance is involved
- Use RLA (not MCA) for compressor motors; use FLA for blower/fan motors
- Count circuits, not appliances, for Small Appliance and Laundry fields
- Treat a gas range/oven's igniter-and-controls load as a real (if small) Fixed Appliance entry, not an automatic zero
- Document spare/unused circuits and any non-default demand factor in the Note field rather than omitting silently
- Round gross sq ft up slightly when uncertain
- Enter both solar PV and battery storage if paired — don't assume they net to zero
- Default Custom Load demand factor to 1.0 unless you have a specific, citable reason to lower it
Don't:
- Double-count a circuit in both the SA/Laundry dropdowns and as a Custom Load
- Add VA for anything already covered by the sq ft × 3 VA general allowance (general lighting/receptacles, low-voltage systems)
- Use MCA where RLA is the correct figure
- Count an unused/spare circuit's load when calculating present-day actual demand — note it instead
- Try to fold the garage's square footage into the main sq ft field
- Add a line item just because a circuit is GFCI/AFCI-protected — protection method ≠ load category
- Lower a Custom Load's demand factor below 1.0 without a citation or clear written justification