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POE PLANNING

How to Calculate a PoE Switch Power Budget

Separate per-port capability, powered-device requirement and total switch power budget.

The basic planning calculation

CALCULATED: total planned endpoint load = sum of quantity x entered watts for each device group.

USER ASSUMPTION: optional planning headroom can be added by the designer. Headroom is not itself an IEEE requirement and should be labelled as an assumption.

Three checks

  1. Does each PD fit the capability of its individual PSE port?
  2. Does the total of the planned PD loads fit within the switch's published PoE budget?
  3. Does the upstream switch power supply and UPS design support the resulting switch input load?

Example method

If an installer enters 8 cameras at 12 W each and 4 access points at 18 W each, the arithmetic load is 168 W. Those device wattages are only valid if they came from the actual device specifications or measured design values. The calculation does not prove PoE compatibility or account for switch-specific allocation behaviour.

IMPORTANT: use manufacturer-published PD requirements and switch budget values. Do not use generic camera or AP wattages as design facts.

Open the PoE Budget Planner | Back to PoE Field Guide

Technical references

These sources support the standards, test-method and manufacturer-specific statements on this page. Project specifications and current manufacturer documentation take precedence for a real installation.