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PoE power budget calculator.
Enter your switch's total PoE budget and up to four groups of devices. For each group give the count, watts per device and the PoE standard of the port.
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PoE Power Budget Calculator: how it works
The IEEE 802.3 PoE standards define how much power a switch port (the power sourcing equipment) can supply and how much is guaranteed to arrive at the device. Per Wikipedia's Power over Ethernet article: 802.3af (Type 1) supplies up to 15.4 W with 12.95 W at the device; 802.3at (Type 2, PoE+) 30 W with 25.5 W at the device; 802.3bt Type 3 60 W with 51 W; and Type 4 90 W with 71.3 W. The difference is power dissipated in the cable.
The tool shows two totals. Actual draw adds the watts your devices really use. Class allocation assumes each port is reserved at the full power of its standard (15.4, 30, 60 or 90 W), which is what a switch that allocates by class would hold back. It also warns if a device draws more than its standard delivers at the device.
Worked example. A 120 W switch powers 4 cameras at 10 W on 802.3af ports and 2 access points at 20 W on 802.3at ports. Actual draw = 4 x 10 + 2 x 20 = 80 W (67% of budget). Class allocation = 4 x 15.4 + 2 x 30 = 121.6 W, which is 1.6 W over the 120 W budget, so a class-allocating switch could refuse to power the last device.
Frequently asked questions
How much power does PoE deliver?
802.3af gives up to 15.4 W per port (12.95 W at the device), 802.3at 30 W (25.5 W), 802.3bt Type 3 60 W (51 W) and Type 4 90 W (71.3 W).
What is the difference between actual draw and class allocation?
Actual draw is what devices use. Class allocation reserves the full power of each port's standard. Check your switch manual to see which method it uses.
Why does my device get less than the switch supplies?
Some power is dissipated in the cable, so the power available at the device is lower than the port maximum.
Can a switch supply its full PoE budget on every port?
Not necessarily. The total budget is shared across ports, so the sum of what you plug in has to stay under it.
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Not professional advice
Planning aid only, not electrical or professional advice. Use the switch and device datasheets for real figures and follow manufacturer limits.