Methodology / worked examples
PortPlan PoE Budget guide
A switch can have enough physical sockets but still lack the PoE watts needed by its connected devices. PortPlan keeps those constraints visible, while leaving exact class and draw claims to the documentation you enter.
Count user ports after uplinks
Enter every physical switch port, then reserve ports used to connect upstream equipment. The remaining ports are the slots available to the device list.
user ports = switch ports - uplink ports
A 16-port switch with 2 reserved uplinks leaves 14 user ports.
Use peak per-port demand
For each row, use the documented maximum or a measured planning value. Quantity multiplies both port occupancy and watts. PoE class is a label for review, not a substitute for the device specification.
total PoE demand = sum(per-port W x quantity)
Three access points at 25 W each and four cameras at 8 W each need 107 W before headroom.
Leave buying headroom
Apply a deliberate reserve for future additions and uncertainty, then compare that recommendation with the switch power budget. A switch may also impose a separate per-port limit.
recommended budget = total demand x (1 + headroom / 100)
A 107 W list with 20% headroom suggests 128.4 W of budget.
Limits and assumptions
- This is a port and power worksheet, not a coverage simulation, cable certification, or guaranteed device compatibility check.
- Per-port watts and PoE class must come from the actual device and switch documentation. Negotiated draw can differ from a nameplate maximum.
- It does not select a live product, verify VLANs, or estimate wireless capacity.