sysop@hub:~/tools/poe-budget-calculator$
poe-budget-calculator
Can the switch feed everything that is plugged into it? Enter the PoE budget from the data sheet and how many devices of each class it has to power.
devices to power
the standards
| Name | Standard | At the switch port | Arrives at the device | Typical devices |
|---|---|---|---|---|
| PoE | 802.3af, Type 1 | 15.4 W | 12.95 W | Phones, simple cameras, older access points |
| PoE+ | 802.3at, Type 2 | 30 W | 25.5 W | Current access points, PTZ cameras |
| PoE++ | 802.3bt, Type 3 | 60 W | 51 W | Wi-Fi 6E and 7 access points, thin clients |
| PoE++ | 802.3bt, Type 4 | 90 W | 71.3 W | Displays, small switches, lighting |
The difference between the two power columns is lost as heat in up to 100 m of cable. The class of a device is in its data sheet, often as "802.3at" or "PoE+ required". "Passive PoE" on some cameras and radio links is not part of these standards: it puts a fixed voltage on the cable without asking, and can damage a device that does not expect it. A switch's total budget is usually well below ports times 30 W: a 24-port PoE+ switch with 370 W can run twelve ports at full power, not twenty-four. Related: small office blueprint, switching and VLAN cheat sheet, connector identifier, UPS runtime calculator.