What size service does a typical house need?

Most new homes in 2026 are built with 200-amp service. Smaller homes without electric heat or EV charging may work with 150A. Larger homes with multiple high-draw appliances, EV chargers, and electric heating may need 320A or 400A service.

What is the difference between connected load and demand load?

Connected load is the sum of all appliance nameplate ratings. Demand load applies NEC demand factors that account for diversity (not everything runs at full load simultaneously). Demand load is always lower than connected load and is what determines service sizing.

Do I need a permit for a panel upgrade?

Yes. In virtually all jurisdictions, upgrading the electrical panel or service requires a permit and inspection. The utility company must also be involved to upgrade the meter and service entrance cables.

How many circuits do I need?

NEC requires dedicated 20A circuits for kitchen countertop receptacles (minimum 2), one 20A laundry circuit, one 20A bathroom circuit, and dedicated circuits for each major appliance. General lighting is served by 15A circuits, each covering approximately 600 sq ft.

Construction & Engineering

Electrical Load Calculator

Calculate residential panel amperage, service size, and circuit requirements using 2026 NEC Article 220 demand factors.

Home Size (sq ft)

Service Voltage

Major Appliances (watts)

Range / Oven

Clothes Dryer

Water Heater

Dishwasher

HVAC (watts)

Air Conditioning

Electric Heat

NEC uses the larger of heating or cooling.

Additional Loads (watts)

EV charger, pool pump, hot tub, workshop, etc.

Your Results

⚡

Enter home details and click calculate.

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Introduction

This Electrical Load is designed for professionals who need accurate and reliable calculations in their daily work. Whether you are planning finances, managing projects, or making critical business decisions, having the right numbers at your fingertips is essential. This tool provides instant results based on proven formulas, saving you time and reducing the risk of manual calculation errors. By using this calculator, you can focus on analysis and decision-making rather than spending time on complex computations. The interface is straightforward and designed for practical use, ensuring that you get the information you need quickly and efficiently.

What This Calculator Does

This residential electrical load calculator estimates the total service amperage and panel size needed for a home using the 2026 National Electrical Code (NEC) Article 220 Standard Calculation method. It applies NEC demand factors to general lighting, small appliance circuits, and major appliances to determine the calculated demand load. The tool recommends service size (100A, 150A, 200A, or 400A) and provides a circuit breaker breakdown for panel layout planning.

The Formula

Demand Load = Lighting Demand + Range Demand + Dryer Demand + Appliance Loads + HVAC Load | Amps = Demand Load (VA) / Voltage

The NEC Standard Calculation starts with general lighting at 3 VA per square foot, plus two small appliance circuits (3,000 VA) and one laundry circuit (1,500 VA). A demand factor is applied: the first 3,000 VA at 100% and the remainder at 35%. Ranges up to 12 kW use an 8 kW demand per NEC Table 220.55. Dryers use the nameplate rating or 5,000 watts minimum per NEC 220.54. HVAC uses the larger of heating or cooling per NEC 220.60. The total demand in VA divided by the service voltage (typically 240V) gives the required amperage.

Step-by-Step Example

Enter home size

A 2,000 sq ft home has a general lighting load of 6,000 VA (2,000 x 3 VA/sq ft).

Enter major appliances

Range: 12,000W. Dryer: 5,500W. Water heater: 4,500W. Dishwasher: 1,500W.

Enter HVAC loads

AC: 5,000W. Electric heat: 10,000W. NEC uses the larger value: 10,000W.

Review service sizing

Total connected: 42,500 VA. After demand factors: approximately 35,700 VA. At 240V: 149 amps. Recommended: 200-amp service.

Real-World Use Cases

New Home Construction

Determine the correct service size and panel capacity during the design phase to avoid costly service upgrades later.

Service Upgrade Evaluation

Determine whether a homeowner adding an EV charger, hot tub, or workshop needs to upgrade from 100A to 200A service.

Permit Applications

Provide load calculations to support electrical permit applications required by most jurisdictions for new construction or service upgrades.

Common Mistakes to Avoid

Adding up all appliance nameplate ratings without applying NEC demand factors. The demand calculation accounts for the fact that not everything runs simultaneously.
Using the sum of heating and cooling loads. NEC 220.60 specifies using the larger of the two because they do not operate at the same time.
Forgetting future loads. If the homeowner plans to add an EV charger (7,200W to 11,500W), include it now to avoid a service upgrade later.
Not accounting for NEC Table 220.55 demand factors for ranges. A 12 kW range uses only 8 kW for load calculation purposes, not the full nameplate rating.

Frequently Asked Questions

Accuracy and Disclaimer

This calculator uses the NEC Article 220 Standard Calculation method for residential load estimation. Local jurisdictions may adopt amendments to the NEC that change requirements. This tool is for planning and estimation purposes. A licensed electrician must perform the official load calculation for permit applications. Always hire a licensed electrical contractor for installation work.

Conclusion

This calculator provides a reliable way to perform essential calculations for your professional needs. The results are based on standard formulas and should be used as estimates for planning and analysis purposes. For critical decisions, especially those involving financial, legal, or medical matters, it is always advisable to verify results with a qualified professional. Use this tool as part of your broader decision-making process, and explore related calculators on this platform to support your comprehensive planning needs. Regular use of accurate calculation tools helps ensure consistency and precision in your professional work.

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