POWER OVER ETHERNET PLANNING TOOL
Size a PoE switch for IP cameras, PTZ cameras, Wi-Fi access points, VoIP phones and access-control devices. Check total watts, available ports, cable loss, engineering headroom and IEEE 802.3af, 802.3at or 802.3bt per-port limits.
Set the engineering assumptions and design parameters.
Use the maximum device draw, not the marketing average. Night-mode infrared, heaters, radios and USB accessories can increase demand.
Review calculated capacity, limits and design checks.
Count every camera, wireless access point, phone, intercom and door controller that will draw power at the same time. The port count is a hard limit even when watts remain.
Use the device datasheet maximum at the powered-device input. A PTZ motor, IR illuminator or Wi-Fi radio under load can consume more than its normal idle value.
Ethernet cable dissipates power. Add an estimated cable-loss allowance and reserve operational headroom for startup, temperature, expansion and power-supply aging.
IEEE 802.3af PoE commonly supports devices up to 12.95 W at the powered device, while 802.3at PoE+ increases that to 25.5 W. IEEE 802.3bt uses four pairs: Type 3 supports up to 51 W delivered and Type 4 up to 71 W delivered. Switch vendors may advertise the source-side figure, so compare device demand with delivered PD power and compare the full deployment with the switch’s total PoE budget.
A 24-port switch is not automatically able to power 24 high-load devices. For example, twenty-four 15 W devices need 360 W before cable loss and reserve are considered. Conversely, a 370 W switch may still be limited by port count or by a per-port standard that cannot start a high-power PTZ camera. This PoE switch sizing calculator checks all three constraints.
When asking “how many PoE cameras can my switch support?”, enter the camera’s highest specified draw, the number of PoE-capable ports and the switch budget shown in the switch datasheet. For surveillance, include infrared night mode, heaters and pan-tilt-zoom operation. For Wi-Fi 6E or Wi-Fi 7 access points, include peak radio load and any downstream USB or pass-through power. A 20–25% reserve can be used as a project starting assumption, but it is not an IEEE requirement. Set the final margin from measured peaks, startup behavior, cable conditions, expansion plans, power-supply configuration and availability targets.
It depends on maximum camera watts, cable loss, reserve and ports. Eight 10 W fixed cameras may fit comfortably, while eight 15 W cameras can exhaust the budget after loss and headroom.
Yes. Longer or higher-resistance cabling increases I²R loss. This calculator models loss as a planning percentage; verify conductor gauge, category, bundle temperature and run length for final design.
Use maximum rated or measured demand for capacity planning. Average values can hide boot surges, IR activation, PTZ motors and high radio utilization.
PASS means the entered design meets total watts, available ports and per-port power class with the selected assumptions. It is an engineering estimate, not a substitute for manufacturer requirements or electrical safety review.
No. Headroom is a project planning choice, not a universal IEEE requirement. Select it from measured peak load, startup behavior, cable conditions, expansion plans, power-supply configuration and the availability target.
The cable-loss percentage is a planning input, not a complete IEEE channel simulation. Final design should verify PSE and PD classes, negotiated allocation, power-supply and redundancy state, cable channel, bundle temperature and device startup behavior. Last reviewed: 2026-08-31.
ENGINEERING WORKFLOW
Verify PoE source capacity, cable voltage delivery, rack power and cooling, then estimate telecom battery backup runtime.
