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PoE Power Budget Calculator

IEEE 802.3af / at / bt · PSE Budget · Cable Loss

When to use: Use this calculator when sizing a PoE switch or midspan for cameras, access control, intercoms, APs and IP speakers. It sums multiple device groups, applies the correct IEEE 802.3af / at / bt class, adds DC cable-run loss, and checks the total against the switch's PoE power budget and port count. Remember the difference between PSE power (what the switch reserves/delivers) and PD power (what the device receives after the 100 m channel). Plan for ~20% headroom.

Switch / PSE Parameters
Total PoE
W
ports
Device Groups
Group 1
units
optional
W
ft
✓ PASS — Within Budget
14%
Power Budget Used · 86% headroom
Device Power Table
DeviceQtyClass / StdPD W eaCable LossPSE W eaGroup PSE WPorts
Fixed IP camera4802.3af · Class 312.90.4413.453.64
TOTAL451.81.7653.64
* actual PD watts override · ⚠ device PD exceeds declared class · PSE W ea = PD load + cable loss (or class allocation when larger)
Budget Summary
Total PD Load51.8 W
Total Cable Loss1.76 W
Total PSE Draw (actual)53.6 W
Total PSE (class allocation)61.6 W
Switch Power Budget370 W
Headroom316 W (86%)
Ports Used / Available4 / 24
Recommendation

Within budget with 86% headroom and 4/24 ports used. Healthy margin for the PoE switch.

References
IEEE 802.3af — PoE Type 1: 15.4 W PSE / 12.95 W PD
IEEE 802.3at — PoE+ Type 2: 30 W PSE / 25.5 W PD
IEEE 802.3bt — PoE++ Type 3 (60 W) / Type 4 (90 W PSE)
PSE = port allocation · PD = power after 100 m channel
Cat5e 24AWG ≈ 0.0257 Ω/ft · Cat6 23AWG ≈ 0.0202 Ω/ft (per conductor)
Derate for bundled cables & high ambient temperature
Plan ~20% switch power-budget headroom for growth