Power over Ethernet Calculator

Calculate PoE power budget and cable losses.

PoE Standard / Class

Cable Length

Cable Type

Device Power Requirement (Watts) Leave blank to show maximum available

PoE Standards Reference

Standard	PSE Power	PD Power	Pairs
802.3af (PoE)	15.4W	12.95W	2
802.3at (PoE+)	30W	25.5W	2
802.3bt Type 3	60W	51W	4
802.3bt Type 4	90W	71.3W	4

PoE Power Budget Considerations

Cable Loss Factors

Resistance increases with cable length
Thinner wire (higher AWG) = more resistance
Temperature affects resistance
802.3bt uses all 4 pairs to reduce loss

Best Practices

Keep cable runs under 100m per standard
Use Cat6/Cat6a for high-power PoE
Allow 20% power margin for reliability
Consider ambient temperature effects
Check switch PoE budget for multiple devices