Count the watts before you buy the switch.
Every AP and camera draws PoE power, every switch has a fixed budget, and the failure mode is gear that randomly reboots under load. Add your devices below — the calculator sums the measured draw and shows which switch fits with proper headroom.
Your powered devices
Draw figures are from our bench under load — lower than the datasheet maximums, real enough to plan on. The 20% headroom rule is applied for you.
0 POE PORTS · 0 W WITH 20% HEADROOM
Add devices on the left. The bars show how much of each switch's PoE budget your kit would use — green is comfortable, amber is tight, red doesn't fit.
The sizing rules behind the math
Three rules, none of them complicated. They're the difference between a switch that runs for a decade and one that mystery-reboots every August.
Plan on measured draw, buy on headroom
Datasheet maximums overstate steady-state draw, but heat and firmware change over years. We size to bench-measured numbers plus 20% — the calculator's amber zone starts where that headroom ends.
Count ports and watts separately
A switch can have watts to spare and no PoE ports left, or the reverse. Eight cameras at 4.5 W fit a Lite 8's budget easily — but the Lite 8 only powers 4 ports. The calculator checks both.
Match the PoE class, not just the total
A PoE+ AP on a PoE-only port boots, browns out, and reboots — the most misdiagnosed fault we see. Every product page lists the class; when in doubt, the answer is on the support bench.
Past ~16 powered devices, get a design.
Multiple switches, PoE++ cameras, and long cable runs change the math. Send the device list through design help and an installer specs the whole closet — free.