Power over Ethernet calculator ( PoE ) to find Line Loss

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injectors - 5v to 56v

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The PoE calculator by PoE-Texas calculates the total power required for any device including cable loss by any type or length of cable, over Ethernet or not, it calculates the voltage drop and power required by both the device and the loss in the cable. Since a device is speced for power consumption over a range of input voltages, as the remotely delivered voltage decreases with distance, the amps increase, causing the delivered voltage to decrease further.

The WiFi-Texas calculator is the first to calculate total power including the effects of voltage drop.

A Number of pairs used for POE
1 simple wire
2 802.3af, standard
4 PoE+
Ethernet over Coax
BCable type
Cat-5e Copper
Cat-6 Copper
Cat-7 Copper
Cat-5e low cost Cu/Al
Cat-6 low cost Cu/Al
Cat-5e cheap
RG-59/U Coax 22 awg center
RG-6/U Coax 18 awg center
RG-11/U Coax 14 awg center
Or enter other
Ohms/1000 ft
see AWG table below
CDistance in ft
(328 is max for Ethernet)
or Meters

DSupply Voltage (56v max)
802.3at 56 Volts
802.3at 51 Volts
802.3af 48 Volts
UBNT/MT 24 Volts
12 volt
5 voilts 
USB  5 Volts
or enter other
EPower required by remote device
FNumber of Devices to power

Cat-5e and Cat-6 cable is sold in pure Copper and in Copper / Aluminum alloy ( Cu/AL ) variations.
Cu/Al is standard at Home Depot etc, and unless specified, assume all CAT-5 isn't copper
Cu/Al has higher resistance, so the loss is greater.
There is also extremely low cost cable that uses thinner 28 AWG wire on the 45 and 78 pairs, resulting in high loss.
PoE via coax allows 300 ft of CAT-6 then 800 ft of coax then 300 ft of cat-6 for a total of 1400 ft. Calculate the final voltage in three segments.

Our Calculator will give a warning if the link is too long
At long distances, the result is unstable and cannot be solved
we will suggest minimum voltages for the length entered

If you have more than one device per endpoint
change the value in line F

Chinese CCA cat-5 uses 28 awg on the power pairs @ 101 ohms

one CAT-5e spec

Ohms per 100 ft at different temperatures