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PoE Budget Planner

Add up powered devices by PoE class or measured draw, account for cable loss over distance, and compare the total against your switch's power budget. Shows headroom, per-port averages, and whether you are about to brown out an access layer.

Take this from the datasheet — the PSU rating is a different number.

  • 184.8 W reserved
  • 180.0 W reserved
364.8 WClass allocationWhat the switch reserves — plan against this
5.2 WHeadroom99% of a 370 W budget
162.0 WMeasured drawTypical steady state
18PoE ports used
20.3 WAvg per port
370 WSwitch budget
Method & assumptions
  • Switches allocate power by class, not by actual draw. A camera pulling 6 W on a Class 4 port still reserves 30 W unless the switch uses LLDP-based allocation.
  • Class wattages are the PSE-side figures from 802.3af/at/bt, which already include the standard's cable-loss allowance to 100 m.
  • Measured draw is shown as the lower bound. Size a PSU or a UPS against it; plan ports against the class allocation above.
  • Aim to stay under about 90% allocated so a replacement device or a failover has somewhere to go.
The guide behind it

PoE Standards and Why It Won't Power

The budget is arithmetic; the reason it runs out is class allocation. The guide covers what each class reserves against what the device actually receives.

Read the guide

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More on the bench

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