Estimate subpanel size, feeder breaker size, feeder wire size, panel load percentage, remaining capacity, and voltage drop from planned loads, voltage, phase type, distance, and conductor material.
Load conversion:
The calculator converts amps, watts, or kilowatts into load amps based on voltage and phase type.
Adjusted load:
Demand factor and continuous load factor are applied to estimate the subpanel load.
Subpanel and feeder:
The adjusted amps are used to estimate subpanel size, feeder breaker size, feeder wire size, and voltage drop.
A subpanel size calculator helps estimate the panel and feeder size needed for a garage, workshop, shed, addition, equipment area, or detached structure.
It can help with planning feeder breakers, feeder wire, subpanel capacity, voltage drop, remaining capacity, and rough electrical project sizing before professional review.
Your result shows recommended subpanel size, feeder breaker size, feeder wire estimate, adjusted load amps, panel load percentage, remaining capacity, voltage drop, final voltage, feeder distance, and comparison scenarios.
Estimate the loads the subpanel will serve, apply any demand or continuous load factors, then choose a subpanel and feeder that can safely handle the calculated load.
No. A subpanel adds breaker spaces and distribution, but the total available capacity is still limited by the main service, main panel, feeder, and calculated load.
Many garages use 60A to 100A subpanels depending on tools, outlets, lighting, HVAC, EV charging, and future plans.
No. This is a simplified planning tool. Final subpanel sizing depends on local code, feeder breaker size, conductor size, grounding, neutral separation, voltage drop, service capacity, and inspection requirements.