PoE Budget and Run Distance

Power available at PD over Cat5e/6/6A given PoE class and run length.

Run the calculator

Example

You enter

PoE class at
Cable category Cat6
Run length (ft) 200
Ambient temp (°C) 25

You get

Pse (W) 30
Pd min (W) 25.5
Power available at PD 28.21
Cable I²*R loss 1.79 W
Status green

Details, formula, and sources

I = pse_W / V_source; loop resistance R = R_per_100m × (L / 100m) × (1 + α × (T − 20°C)); P_loss = I² × R; PD power = pse_W − P_loss; flagged against IEEE 802.3 class minimums.

IEEE 802.3bt-2018 by name; manufacturer category cable resistance (Belden / CommScope) attributed in shard.

IEEE 802.3 free at standards.ieee.org/getieee802. Cable specs free at each manufacturer site.

Estimate. AHJ and licensed electrician govern. Verify against the NEC edition adopted in your jurisdiction.

Field names used by the API: poe_class, category, run_length_ft, ambient_C, pse_W, pd_min_W, pd_available_W, cable_loss_W, flag

Copper temperature coefficient α = 3.93 × 10⁻³ /K at 20°CNIST
Class minimum PD power af 12.95 W / at 25.5 W / bt3 51 W / bt4 71.3 WIEEE 802.3bt-2018