PoE PD Trace Width Calculator (802.3af/at/bt)
Trace sizing for PoE powered devices — per-class currents, 4-pair splitting and the isolation rules that matter more than width.
Preset for this niche — adjust to your stack-up. IPC-2221 assumes still air; verify hot paths with a thermal camera.
PoE PD Trace Width Calculator computes trace sizing and isolation rules for PoE powered devices — free, instant and private in your browser. Designers of cameras, access points and IoT gear fed over Ethernet use it to skip the datasheet algebra: type your numbers, read the answer with the substituted formula shown step by step, and share an exact permalink of the calculation.
About PoE PD Trace Width Calculator (802.3af/at/bt)
PoE PD Trace Width Calculator computes trace sizing and isolation rules for PoE powered devices using the standard engineering relation: IPC-2221 with PD presets: 1.2 A at 48 V (802.3bt) — currents are modest, clearances are the design. Worked live: even 71 W class-8 PoE is only ~1.7 A at the PD input — a 0.8 mm trace carries it; your DC-DC's 12 V side needs far more. The result recalculates on every keystroke, the worked-example panel shows your numbers substituted into the formula, and the Copy permalink button encodes the inputs in the URL so a colleague opens exactly your calculation. Everything runs client-side — nothing you type leaves your device.
How to use PoE PD Trace Width Calculator (802.3af/at/bt)
- 1Enter your values — the tool starts with realistic defaults for this exact use case, so the worked example is meaningful immediately.
- 2Read the live result and the worked-example panel, which substitutes your numbers into the formula step by step.
- 3Adjust any input to compare scenarios, then use Copy result or Copy permalink to share the calculation.
Why use PoE PD Trace Width Calculator (802.3af/at/bt)?
- ✓Implements the real formula — IPC-2221 with PD presets: 1.2 A at 48 V (802.3bt) — currents are modest, clearances are the design — with the substitution shown, not a black box
- ✓Built for designers of cameras, access points and IoT gear fed over Ethernet
- ✓Copy result and permalink buttons — share the exact calculation in a README, forum answer or design review
- ✓100% free, no sign-up, runs entirely in your browser (works offline once loaded)
Frequently asked questions
How do you calculate poe pd trace width?+
Trace sizing and isolation rules for PoE powered devices follows IPC-2221 with PD presets: 1.2 A at 48 V (802.3bt) — currents are modest, clearances are the design. For example, even 71 W class-8 PoE is only ~1.7 A at the PD input — a 0.8 mm trace carries it; your DC-DC's 12 V side needs far more. The calculator applies the same relation and shows the substituted arithmetic so you can verify every step.
Why does the LOW-voltage side need fatter traces than the 48 V side?+
Watts are conserved through your converter: 25 W arriving at 0.6 A leaves a 5 V rail at 5 A. The 48 V input romance distracts from the secondary, which carries 8× the current — size the output stage like any 5 A supply.
What isolation must a PD design maintain?+
1.5 kV between the cable side and any user-accessible circuit — provided by the Ethernet magnetics plus your isolated DC-DC. On the PCB that's an unbroken creepage moat: no pours, traces or silkscreen bridging the boundary, slots where spacing is tight. The transformer is the only legal crossing.
Is the PoE PD Trace Width Calculator free and private?+
Yes — completely free with no sign-up or usage limits, and it runs entirely in your browser: the values you enter are never uploaded or stored on a server.
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