Use this online panel load schedule calculator to total branch-circuit loads, apply demand and spare capacity, estimate panel current, and choose a practical main breaker size.
A panel load schedule calculator helps estimate how heavily a distribution panel will be loaded based on the branch circuits connected to it. It totals the circuit loads, applies a demand factor, adds spare capacity for future growth, and converts the resulting panel demand into current and a likely main breaker size.
This panel schedule calculator is useful for electrical distribution boards, subpanels, and main panels in residential, commercial, and small industrial systems. It helps you build a quick load schedule and estimate whether the panel main rating is in a practical range.
It is particularly helpful when organizing branch loads into a clearer panel overview so future expansion and spare capacity can be considered at the same time.
| Variable | Meaning | Typical Unit |
|---|---|---|
| Pconnected | Total of all listed circuit loads | W |
| Pdemand | Panel load after diversity or demand factor | W |
| Pdesign | Panel load after adding spare capacity | W |
| PF | Power factor used for current calculation | Unitless |
| I | Estimated panel main current | A |
Enter circuit loads in watts, demand and spare factors in percent, voltage in volts, and power factor as a decimal between 0 and 1.
Results are shown in kilowatts and amperes so they can be used more easily during panel design and load schedule review.
Circuit loads: 800, 1200, 1500, 900, 500, 1100 W
Connected load = 6000 W
Demand load at 80% = 4800 W
Design load with 20% spare = 5760 W
At 230 V and PF 1.0, current = 5760 / 230 = 25.04 A, so a practical main breaker is 32 A.
Circuit loads total 18000 W, demand factor 75%, spare 25%, voltage 400 V, PF 0.9.
Demand load = 13500 W
Design load = 16875 W
Current = 16875 / (sqrt(3) x 400 x 0.9) = 27.06 A, so a practical main breaker is 32 A.
A panel load schedule should be reviewed whenever new circuits are added, major equipment is replaced, or a building is expanded. Tracking connected load, demand load, and spare capacity helps keep panelboards practical, safe, and easier to maintain. This panel load schedule calculator gives a useful early-stage estimate for main rating and load distribution, but final electrical drawings should still confirm circuit balance, spare ways, and protection requirements for the completed installation.