PoE Budget Calculator
Estimate switch PoE power needs by device count and IEEE 802.3 power standard
What does a PoE budget calculator do?
This calculator estimates the power-over-Ethernet budget a switch should provide for connected powered devices. It uses the maximum power each IEEE PoE class can source per port, then adds a 20% planning reserve.
How to estimate a switch PoE budget
- Enter the switch’s available PoE power budget in watts.
- Enter device counts for each supported IEEE 802.3 PoE standard.
- Compare the conservative estimated load and reserve with the switch budget.
Example: Estimate PoE switch power
For four 802.3af devices and four 802.3at devices, the conservative port allocation is (4 × 15.4 W) + (4 × 30 W) = 181.6 W. Adding the calculator’s 20% reserve gives a recommended switch budget of 218 W after rounding up. Compare that estimate with the switch’s available PoE budget.
Important sizing assumptions
The calculator uses up to 15.4 W for 802.3af, 30 W for 802.3at, 60 W for 802.3bt Type 3, and 90 W for 802.3bt Type 4 per port. Actual device draw is often lower. For a more precise design, use each device’s maximum input power and verify the switch’s per-port limits, power supply configuration, and total PoE budget.
Planning access point coverage as well as switch power? Try the free Wi-Fi Heatmap Planner to map estimated AP coverage on a floor plan, or learn about NETCUE's network design and implementation service for site-specific planning.
Frequently Asked Questions
No. It is a conservative planning estimate based on standard maximum port power. Verify the exact switch model’s total budget, per-port power limits, power-supply configuration, and the connected devices’ requirements.
A reserve helps accommodate startup peaks, future devices, and uncertainty in the estimated loads. It is a planning allowance, not a substitute for checking the manufacturer’s specifications.
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