Work out how many powered devices a switch PoE budget supports once per-device class power and cable loss are counted.
PoE budgets are quoted at the switch, but the device draws its class power at the far end of a cable that dissipates some of it. Adding a loss allowance before summing is what stops a switch that looks adequate on paper from shutting ports down. PoE switches drop ports silently when the budget is exceeded, and the devices that lose power are rarely the ones you would have chosen.
PoE Device Count
Required watts = devices × per-device draw × (1 + cable loss)
Required watts = devices × per-device draw × (1 + cable loss) PoE budgets are quoted at the switch, but the device draws its class power at the far end of a cable that dissipates some of it. Adding a loss allowance before summing is what stops a switch that looks adequate on paper from shutting ports down.
PoE switches drop ports silently when the budget is exceeded, and the devices that lose power are rarely the ones you would have chosen.
This calculator takes 4 inputs: Powered devices, Power draw per device, Switch PoE power budget, Cable loss allowance. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.