Electrical
NEC Load Calculator
Size a residential service per NEC Article 220 standard method. Demand factors for general lighting, cooking, dryers, fixed appliances, HVAC, EV chargers, and motors applied automatically.
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Property
Calculation method
Standard method (NEC 220 Part III)More tedious
Itemize every load that will be on the service. Each demand factor (general lighting, cooking, dryers, fixed appliances, HVAC, motor) applies separately per its own NEC table. Skip nothing — leaving out a real load undersizes the service.
When to use: new construction, or any time the AHJ asks for the "long-form" calculation. Always defensible — never wrong to pick this.
Switch to Optional if this is a one-family dwelling getting solar, storage, or EV added — it's faster and typically gives a 10-15% smaller answer.
Cooking equipment NEC 220.55
Ranges, ovens, cooktops. Demand factor by count.
Subtotal: 12,000 VA
Electric dryers NEC 220.54
5000 VA minimum per dryer. Demand factor by count.
Subtotal: 5,000 VA
Fixed appliances NEC 220.53
Water heater, dishwasher, disposal, hardwired microwave, washer, hot tub, pool pump, etc. 75% demand factor when 4 or more.
Subtotal: 6,825 VA
HVAC heating NEC 220.60
Furnaces, heat pumps (heating side), electric resistance heat. Larger of total heating vs total cooling counts.
HVAC cooling NEC 220.60
AC units, heat pumps (cooling side). Larger of total heating vs total cooling counts.
Subtotal: 4,800 VA
Other (continuous) loads NEC 230.42(A) / 625.42
EV chargers, pool heaters, and other continuous loads. Service is sized at 125% of these per NEC 230.42(A); EVSE specifically per NEC 625.42.
Subtotal: 7,200 VA
Enter VA of the largest motor on the service (typically the AC compressor or pool pump). The 25% adder is applied in addition to the motor's own VA, which should already be listed in HVAC, Fixed, or Other above.
Recommended service
175
A AutoCalculated load: 172.6 A at 240 V (Standard method)
Tight headroom
Using 99% of a 175 A service. Future loads (battery, second EV) would push past 100%.
Service conductor NEC 310.12
About this calculator
NEC-compliant. Free to use. No watermarks.
Load calculations are how you size a service. Get them wrong and you either oversize the panel (wasted money) or undersize it (a violation, and the AHJ rejects the permit).
This calculator runs the NEC Article 220 standard method for dwelling units: 3 VA per square foot for general lighting, 1500 VA per small-appliance and laundry circuit, the Table 220.42 demand factor on general loads, Table 220.55 for cooking, Table 220.54 for dryers, the 220.53 75% rule for four or more fixed appliances, the larger of heating vs cooling per 220.60, and a 25% adder on the largest motor per 220.50. Add an EV charger if there's one. The result is the calculated load in amps and the next standard service size that covers it.
NEC references
- NEC Article 220, Part III: Feeder and Service Load Calculations
- NEC Article 220.82: Optional Method for Dwelling Units
- NEC Article 220.83: Existing Dwelling Unit Calculations
- NEC Table 220.55: Demand Factors for Household Electric Cooking Appliances
The same calculations, running live as you design.
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