Security & Surveillance Tool
Check whether a PoE switch can power all connected cameras, access points and access-control devices — with cable loss, growth headroom and thermal derating applied against the switch PoE budget.
Quick Answer
Add devices by IEEE 802.3 class (af / at / bt) or custom watts, with cable length and type. The calculator adds cable loss per run, subtracts your headroom reserve (and optional hot-cabinet derating) from the switch budget, and reports OK / tight / over with remaining watts.
PoE Load
Add powered devices, their IEEE class or custom watts, quantity, cable length and cable type.
| Device | PoE class | Custom W | Qty | Length (m) | Cable | Source W |
|---|
A sufficient total budget does not guarantee every device powers on. Each device must sit on a port that supports its class — a 60 W device needs an 802.3bt-capable port, not just spare budget in the pool. Check the switch datasheet for per-port class support alongside the total budget.
Formula / Method
Each device row starts from its IEEE per-port ceiling (or custom watts), adds cable loss scaled linearly by length and cable type (Cat5e 15%, Cat6 10%, Cat6a 8% at 100 m), and multiplies by quantity. The switch budget is reduced by your headroom reserve — and by a 0.8 factor when the warm-cabinet toggle is on — before comparison.
Source W = class W × (1 + loss/100m × length) × qty · Usable = budget × (1 − headroom) [× 0.8]
Inputs
Device label, PoE class (802.3af / at / bt Type 3 / bt Type 4) or custom watts, quantity, cable length and cable type per row — plus the switch PoE budget, headroom percentage and optional thermal derating.
Uses
CCTV and access-point rollouts, access-control door controllers, PoE switch selection and upgrades, budget checks before adding cameras to an existing switch, and handover documentation for surveillance installations.
FAQ
The budget is a shared power pool, but every port also has a class ceiling. A 60 W 802.3bt camera will not power up on an 802.3at port even if 200 W of pool is free — the per-port class must match the device. Check both the total budget and per-port class support in the switch datasheet.
Devices draw more than steady-state at cold start (inrush), IR cameras draw noticeably more at night with illuminators on, PSUs deliver less in warm enclosures, and installations grow. A 20–30% reserve absorbs all of that without redesign.
Yes. Power is lost as heat in the conductors (I²R), so the switch must source more watts than the device consumes — the longer and thinner the run, the more loss. Cat6/Cat6a runs lose less than Cat5e thanks to lower conductor resistance. This tool models the loss linearly up to 100 m as a planning approximation.
Learn More
Project
ITCOREOPS can support PoE switch selection, camera and access-point planning, structured cabling and infrastructure handover documentation.
Disclaimer
Planning-level estimate — not a substitute for manufacturer PoE budgets or endpoint datasheets. Verify per-port class support, actual device maximum draw (including night/IR modes and inrush) and switch thermal ratings with the vendor. Not a compliance statement.
Workflow
Use this calculator before specifying a PoE switch, adding devices to an existing one, or documenting a surveillance installation — so budget shortfalls surface on paper, not on site.
Support
For CCTV, access-point and access-control infrastructure, PoE budgets, structured cabling and operational support, visit ITCOREOPS.
Feedback
Report display problems, calculation issues or suggestions for improving this calculator.
Worked example
Inputs: 8× IP camera @ 802.3at (30 W), 30 m Cat6; 4× Wi-Fi AP @ 802.3at (30 W), 20 m Cat6; switch PoE budget 370 W; 20% headroom; no thermal derating.
Result: source draw ≈ 8 × 30.9 W + 4 × 30.6 W = 369.6 W vs a usable budget of 370 × 0.8 = 296 W → utilization ≈ 124.9%, shortfall −73.6 W — over budget. Redistribute across two switches or move to a ~480 W-budget switch.
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