Load Calculator Form
Formula Used
Lighting load = Floor area × Lighting VA per square foot.
Small appliance load = Number of circuits × 1500 VA.
Laundry load = Number of laundry circuits × 1500 VA.
General connected load = Lighting + Small appliance + Laundry + Extra receptacle load.
General demand load = First 10000 VA + Remaining VA × Demand percent.
Fixed appliance demand = Fixed appliance VA × Demand percent.
HVAC demand = Larger value of heating or cooling × HVAC demand percent.
EV demand = Charger watts ÷ Power factor × EV factor.
Motor demand = Largest motor × 125% + Other motor loads.
Total demand = All demand loads + Future allowance.
Feeder amps = Total demand VA ÷ Service voltage.
Panel use = Total demand VA ÷ Panel capacity VA × 100.
How to Use This Calculator
Enter the floor area served by the panel. Add lighting, appliance, laundry, receptacle, cooking, dryer, HVAC, motor, charger, and spare capacity values. Use nameplate ratings when available. Adjust demand percentages only when your design method allows them. Press the calculate button. The result appears above the form.
Download the CSV file for spreadsheet review. Download the PDF file for project notes, client discussions, or early construction planning.
Example Data Table
| Input | Example Value | Reason |
|---|---|---|
| Floor area | 2200 square feet | Typical small home or large accessory space. |
| Small appliance circuits | 2 | Kitchen and dining receptacle planning. |
| Laundry circuits | 1 | Dedicated laundry load allowance. |
| Fixed appliance load | 6500 VA | Dishwasher, disposal, water heater, and microwave. |
| Heating load | 9000 VA | Compared against cooling load. |
| Panel rating | 200 A | Selected service or distribution panel size. |
Electrical Panel Load Planning
A panel load estimate helps builders check whether a service can support planned circuits. It combines lighting, receptacles, appliances, HVAC equipment, motors, chargers, and spare capacity. The result is not a permit design by itself. It is a structured planning report for early construction choices.
What the Estimate Measures
The calculator starts with floor area and a lighting load per square foot. It then adds required small appliance and laundry circuits. Extra receptacle load can be entered when a shop, garage, office, or accessory room needs more plug capacity. Fixed appliances are adjusted with a demand factor when four or more are present. Heating and cooling are treated as noncoincident loads, so the larger value is used. Continuous loads, vehicle chargers, and motors receive higher multipliers because they can stress conductors for long periods.
Why Demand Factors Matter
Connected load is the simple sum of nameplate ratings. Demand load is the expected calculated load after allowed reductions and required increases. A home may have many appliances, yet they rarely run at full output together. A panel also may carry equipment that does run for hours. Good planning balances both facts. That is why the report shows connected load, demand load, feeder amps, spare amps, and panel usage.
Using Results on Site
Use the output to compare a proposed service rating against the expected load. A low usage percentage suggests room for future circuits. A high percentage means the design should be reviewed before rough wiring begins. If the report shows overload, increase the service size, reduce loads, or split equipment onto another approved distribution plan.
Professional Review
Electrical rules change by location, occupancy, and code cycle. Local amendments may change appliance factors, EV charger rules, neutral sizing, continuous load treatment, or feeder requirements. Always confirm the final design with a licensed electrician, engineer, or authority having jurisdiction. This calculator helps organize data before that review. It also gives owners a clear way to discuss options, costs, and future expansion. Keep a copy with plan notes, panel schedules, and equipment cut sheets. Update the numbers whenever appliance models change. Small rating changes can affect feeder size, breaker selection, voltage drop checks, and inspection questions during project review.
FAQs
What is an electrical panel load calculator?
It estimates the total demand placed on a panel. It compares that demand with panel capacity and gives feeder current, spare current, and suggested service size.
Can this replace a licensed electrical design?
No. It is a planning tool. Final service sizing should follow local code, utility rules, equipment listings, and professional review.
Why does the calculator use demand factors?
Demand factors reduce or increase selected loads based on expected use. They help separate connected nameplate totals from realistic calculated demand.
How is heating and cooling handled?
The calculator uses the larger of heating or cooling. These loads usually do not operate at full output together in normal residential planning.
Why is the dryer load at least 5000 VA?
Many planning methods use a minimum dryer allowance. The calculator uses the larger of the entered dryer rating or 5000 VA per dryer.
What does spare current mean?
Spare current is the remaining amp capacity after the calculated demand is subtracted from the selected panel rating.
What should I enter for power factor?
Use the equipment rating when known. Use 1 for simple planning, resistive loads, or when no reliable power factor is available.
When should I increase panel size?
Review panel size when calculated use is high, spare capacity is low, or future equipment may be added soon.