What size electrical service does a new home need in 2026?

Most new homes are built with 200-amp service as a minimum. All-electric homes with heat pumps, EV chargers, and electric cooking may require 320A or 400A service from the start. The 2023 NEC includes new provisions for EV-ready installations that affect required circuit counts in new construction.

What is the difference between connected load and demand load?

Connected load is the sum of every appliance's nameplate wattage. Demand load applies NEC diversity factors that account for the reality that lights, appliances, and HVAC do not all run at maximum simultaneously. Demand load is always lower than connected load and is the correct basis for service sizing.

Do I need a permit for a panel upgrade?

Yes, virtually every jurisdiction requires a permit and inspection for electrical panel replacement or service upgrade. The utility must also disconnect and reconnect service at the meter. Installing a panel without a permit can void homeowner's insurance coverage for electrical fires and causes problems at resale.

Can I do my own electrical work?

Many jurisdictions allow homeowners to do their own electrical work on their primary residence with a permit and inspection. However, utility work at the service entrance must be performed by a licensed electrician in almost all cases. Check your local building department for specific rules before starting any service upgrade work.

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

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Enter home details and click calculate.

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Introduction

Homeowners adding an EV charger, a hot tub, or a home workshop frequently discover that their 100-amp service panel is already at capacity. An unlicensed service upgrade done without a load calculation and permit costs $3,000 to $8,000 to redo when caught at inspection. The 2023 National Electrical Code (NEC) Article 220 Standard Calculation method is the industry framework that determines the minimum service amperage for a residence. It applies demand factors that account for the reality that not every appliance runs simultaneously, which is why a home with 42,500 VA in connected appliances can run on 200-amp (48,000 VA) service. According to the National Electrical Contractors Association (NECA), incorrect service sizing is one of the top causes of failed residential electrical inspections. This electrical load calculator applies the NEC Article 220 method to give you a credible service size recommendation before hiring a licensed electrician.

What This Calculator Does

This residential electrical load calculator estimates total service amperage using the NEC Article 220 Standard Calculation method. Enter floor area, major appliances (range, dryer, water heater), HVAC loads, and any specialty loads like EV chargers or hot tubs. The calculator applies NEC demand factors for general lighting, small appliance circuits, and specific appliances per NEC Tables 220.55 and 220.54. Output includes calculated demand load in VA, required amperage, and recommended service size (100A, 150A, 200A, or 400A).

The Formula

Demand Load (VA) = Lighting Demand + Appliance Demands + HVAC Load | Service Amps = Demand Load / 240V

General lighting load: floor area (sq ft) x 3 VA/sq ft per NEC 220.12. Small appliance circuits: 1,500 VA each x number of circuits (minimum 2 per NEC 210.11). Laundry circuit: 1,500 VA. Combined demand factor: first 3,000 VA at 100%, remainder at 35%. Range demand: NEC Table 220.55 (12 kW range = 8 kW demand). Dryer: nameplate or 5,000 W minimum per NEC 220.54. Water heater, dishwasher, and other fixed appliances: nameplate rating. HVAC: larger of heating or cooling per NEC 220.60. EV charger: 7,200 W for Level 2. Total VA divided by 240V gives required amps. Recommended service size is the next standard size above required amps.

Step-by-Step Example

Enter home floor area

A 2,400 sq ft home has a general lighting load of 7,200 VA (2,400 x 3). Two small appliance circuits add 3,000 VA. One laundry circuit adds 1,500 VA. Combined: 11,700 VA. Applying demand factor: first 3,000 VA at 100% + remaining 8,700 VA at 35% = 6,045 VA lighting/appliance demand.

Enter major kitchen and laundry appliances

Electric range 12 kW: NEC Table 220.55 demand = 8,000 VA. Electric dryer 5,500 W: 5,500 VA. Dishwasher 1,200 W: 1,200 VA. Water heater 4,500 W: 4,500 VA.

Enter HVAC loads

Central AC: 24 amps x 240V = 5,760 VA. Electric heat strips: 15 kW = 15,000 VA. NEC 220.60 uses the larger: 15,000 VA heating load applies.

Total demand and select service size

Total demand: 6,045 + 8,000 + 5,500 + 1,200 + 4,500 + 15,000 = 40,245 VA. Service amps: 40,245 / 240 = 167.7 amps. Recommended service: 200-amp. Adding a 7,200 VA EV charger raises demand to 47,445 VA / 240 = 197.7 amps, still within 200A but close to the limit.

Real-World Use Cases

New Home Service Sizing

A builder designing a 3,200 sq ft all-electric home with electric range, heat pump (18 kW), electric water heater, and EV charger calculates 57,900 VA demand, requiring 241 amps. The design upgrades to a 320-amp service, avoiding a service upgrade request when the homeowner buys a second EV or adds a pool in year three.

EV Charger Addition on Existing Service

A homeowner with a 100-amp service (24,000 VA capacity) wants to add a Level 2 EV charger (7,200 VA). Running the load calculation shows current demand of 21,400 VA. Adding 7,200 VA EV would exceed 100A capacity. A service upgrade to 200A is required before installation, costing approximately $2,500 to $4,500 including panel and utility work.

Service Upgrade Justification for Permit

A homeowner requesting a 200A to 400A upgrade provides the calculated load: existing demand 38,000 VA plus planned hot tub (6,000 VA), home gym with sauna (6,000 VA), and second EV charger (7,200 VA) = 57,200 VA = 238 amps. The calculation justifies a 320A or 400A service to the utility and building department.

Comparison

Service Size	Max Capacity (VA at 240V)	Typical Use Case	Approximate Upgrade Cost
100 Amp	24,000 VA	Small homes, no EV, gas appliances	Existing or $1,500-$2,500
150 Amp	36,000 VA	Mid-size homes, one EV, mixed fuel	$2,000-$3,500
200 Amp	48,000 VA	Most new homes, one EV, all-electric capable	$2,500-$5,000
400 Amp	96,000 VA	Large all-electric homes, multiple EVs, shops	$5,000-$12,000

Common Mistakes to Avoid

Summing all appliance nameplate ratings without applying NEC demand factors. Adding up every appliance at full load overstates actual demand by 40 to 60 percent, since not everything runs at maximum simultaneously.
Using heating and cooling loads together instead of the larger of the two. NEC 220.60 specifies the non-coincident load rule: since heating and cooling do not operate at the same time, only the larger value counts.
Forgetting the EV charger load. A Level 2 EVSE requires a dedicated 240V 50-amp circuit (40A continuous = 9,600 VA). This is a significant load addition that regularly pushes 100-amp services to capacity.
Sizing based on the current loads without planning for future additions. A 200-amp service with 190 amps of demand has no room for growth. Planning for 80 to 85 percent utilization maximum leaves headroom for future additions.

Frequently Asked Questions

Accuracy and Disclaimer

This calculator uses the NEC Article 220 Standard Calculation method for residential load estimation. Local jurisdictions adopt NEC editions on different schedules and may apply amendments. This tool is for planning and estimation only. A licensed electrician must perform the official load calculation for permit applications, and all work must comply with the locally adopted electrical code.

Conclusion

A load calculation is a planning tool, but licensed electrician review is required before pulling a permit or purchasing a panel. If this estimate shows you are near or over your current service capacity, request a formal load calculation from a licensed electrician before ordering equipment. For new construction, combine this output with the Construction Overhead Calculator to budget electrical rough-in as part of your full project overhead. If you are evaluating solar or battery backup additions, account for those loads as well in the initial service sizing.

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