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Electrical Load Calculator

Calculate electrical load and service panel size

Total Load

5.6 kW

Amps

23A

Service Panel

100A

Demand Factor

100%

General lighting: 6,000W auto-calculated

Standard Circuits (NEC)

Kitchen small appliance: 3,000W

Laundry circuit: 1,500W

W
W
W
W
W
W
W
W
W
W
Total Load
5.6 kW
23 Amps
Service Panel
100A
Recommended
General Load
5,625 W
HVAC Load
0 W

Load Distribution

General / Lighting5,625 W

Panel Capacity Usage

23A of 100A panel23%

Good capacity headroom for future expansion

Appliance load0 W
Demand factor100%
This calculator provides estimates based on NEC Article 220. Consult a licensed electrician for actual panel sizing and installation.

Example Calculations

1Average Home (2,000 sq ft, Electric Range, AC)

Inputs

Square Footage2,000 sq ft
Electric Range12,000W
Central AC5,000W
Water Heater4,500W
Dryer5,000W
Dishwasher1,800W

Result

Total Load33,605W (140 amps)
General Demand4,575W
Appliance Load23,300W
AC/Heat Load5,000W
Recommended Service200A

Lighting = 2000 × 3 = 6,000W. Subtotal = 6,000 + 3,000 + 1,500 = 10,500W. Demand = 3,000 + 7,500 × 0.35 = 5,625W. Appliances = 12,000 + 4,500 + 5,000 + 1,800 = 23,300W (75% demand = 17,475W). AC = 5,000 × 1.25 = 6,250W. Total ≈ 29,350W / 240 = 122A → 150A service.

2Small Home (1,200 sq ft, Gas Appliances)

Inputs

Square Footage1,200 sq ft
Central AC3,500W
Dishwasher1,800W
Microwave1,500W
Washer1,200W

Result

Total Load14,344W (60 amps)
General Demand4,785W
Appliance Load3,375W
AC/Heat Load4,375W
Recommended Service100A

Lighting = 1,200 × 3 = 3,600W. Subtotal = 3,600 + 3,000 + 1,500 = 8,100W. Demand = 3,000 + 5,100 × 0.35 = 4,785W. Appliances = 4,500W (75% demand = 3,375W). AC = 3,500 × 1.25 = 4,375W. Total ≈ 12,535W / 240 = 52A → 100A service.

Frequently Asked Questions

Q

How do you calculate residential electrical load?

Use NEC Article 220: General lighting = sq ft × 3W. Apply demand factor (100% first 3kVA, 35% remainder). Add appliance loads. Add largest motor at 125%. Total watts ÷ 240V = amps needed. A 2,000 sq ft home typically needs 100-200 amp service.

  • Step 1: General lighting load = total sq ft × 3 watts (e.g., 2,000 sq ft = 6,000W)
  • Step 2: Add small appliance circuits (2 × 1,500W = 3,000W) + laundry (1,500W)
  • Step 3: Apply demand factor – 100% of first 3,000W, then 35% of the remainder
  • Step 4: Add all fixed appliances (range, dryer, water heater, dishwasher) at 75% demand
  • Step 5: Divide total watts by 240V to get amps, then round up to next panel size
Q

What size electrical panel do I need?

Most homes need 200-amp service. Small homes under 1,500 sq ft may use 100 amps. Homes with electric heat, EV charging, or hot tubs often need 200+ amps. Calculate total load in amps and choose the next standard size up (100, 150, 200, or 400A).

  • 100A panel: sufficient for small homes <1,500 sq ft with gas heat and no EV
  • 150A panel: mid-size homes 1,500–2,500 sq ft with modest electric loads
  • 200A panel: standard for new construction – handles most modern homes up to 3,000 sq ft
  • 400A panel: large homes, dual HVAC systems, EV charging, pools, and workshops
  • Upgrading from 100A to 200A costs $1,500–$3,000 including meter base and panel
Panel SizeHome SizeTypical LoadCost to Install
100A<1,500 sq ft50–80 amps$1,200–$2,000
200A1,500–3,500 sq ft100–180 amps$1,800–$3,500
400A3,500+ sq ft200–350 amps$3,500–$6,000
Q

What is the NEC demand factor?

NEC demand factors reduce the calculated load because not all circuits run simultaneously. General lighting: 100% of first 3,000W, 35% of remainder. Cooking equipment: varies by number of units. These factors prevent oversizing the service.

  • General lighting + receptacles: 100% of first 3,000W, 35% of the rest
  • Example: 10,500W subtotal → 3,000 + (7,500 × 0.35) = 5,625W demand
  • Cooking equipment (1 range): use 8,000W demand regardless of nameplate rating
  • Four or more fixed appliances (not range/dryer): apply 75% demand factor
  • Largest motor load (usually AC compressor): add at 125% of rated amps per NEC 220.50
Q

Do you add AC and heating loads together?

No. Per NEC 220.60, use only the larger of heating or cooling loads since they do not operate simultaneously. If AC is 5,000W and electric heat is 10,000W, use 10,000W in your calculation, not 15,000W.

  • NEC 220.60 allows using only the larger of HVAC or heating – never both
  • Central AC (3–5 ton): typically 3,500–6,000W; add at 125% for motor starting surge
  • Electric furnace: 10,000–20,000W – usually the larger load if you have both
  • Heat pump systems count as cooling load since the compressor is the same unit
  • If you add a hot tub (6,000W) or EV charger (7,200–11,520W), those are always added separately

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Last Updated: Mar 9, 2026

This calculator is provided for informational and educational purposes only. Results are estimates and should not be considered professional financial, medical, legal, or other advice. Always consult a qualified professional before making important decisions. UseCalcPro is not responsible for any actions taken based on calculator results.

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