PoE Switch Power Budget Planner

Size PoE switches without spreadsheets. Enter the aggregate PoE budget and the watts each device consumes to see how many ports you can light up, how much wattage remains after cable losses, and whether you still have headroom for future adds.

Published PoE budget for the switch or stack.
Average wattage required by each camera, AP, or handset.
Optional. Defaults to 5% to cover heat and cable losses.
Optional. Defaults to 20% so you do not strand the budget.

Engineering aid only. Validate PoE budgets with vendor datasheets, NEC derating rules, and on-site measurements before deployment.

Examples

  • 740 W switch, 27 W AP draw, 5% loss, 15% growth reserve ⇒ Deploy up to 22 powered devices • Deployable wattage after losses/headroom: 597.6 W • Watts consumed: 594.0 W • Real-time headroom remaining: 109.0 W • Budget utilization: 84.41%.
  • 480 W compact switch, 17 W camera draw, default 5% loss and 20% reserve ⇒ Deploy up to 21 powered devices • Deployable wattage after losses/headroom: 364.8 W • Watts consumed: 357.0 W • Real-time headroom remaining: 99.0 W • Budget utilization: 78.29%.

FAQ

How do I pick the per-device wattage?

Use the nameplate draw from the datasheet at the PoE class you'll negotiate. For Wi-Fi 6E access points or PTZ cameras, add a few watts of overhead for heaters or radios that only activate under load.

Can I enter different draws for different devices?

Run the calculator separately for each device profile or average their wattage weighted by port count. The lowest resulting device limit controls the entire switch.

What if the math says zero devices?

Increase the switch budget, lower the loss/headroom assumptions, or move high-draw devices to a dedicated midspan so the deployable wattage stays positive.

Does this include AC power supply capacity?

Only the published PoE budget is modeled. Ensure your AC feed and UPS can deliver more than the PoE budget plus the switch chassis requirements.

Additional Information

  • Loss allowance accounts for voltage drop across long cable runs plus PoE conversion inefficiencies.
  • Growth headroom keeps 10–30% of the budget in reserve so maintenance teams can add devices without truck rolls.
  • If you mix Class 3 and Class 6 devices, use the highest draw so the result stays conservative.
  • Compare the deployable device count to port counts—if you have more PoE ports than budget, add another PSU or midspan.

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