Ethernet Cable Calculator

Ethernet cables have strict length limits, and exceeding them causes dropped connections, slow speeds, or PoE devices that won't power on. Select your cable category (Cat 5e, Cat 6, or Cat 6A), cable type (UTP or STP), horizontal cable length, and patch cable gauge to get your Maximum Cable Length and Total Channel Length. Enable Power over Ethernet (PoE) and enter your input voltage, device power requirement, and wire resistance to also see voltage drop, delivered voltage, and power loss.

m

Permanent cable run length

V
W
Ω/100m

Per 100 meters for both conductors

Installation Condition *

Results

Maximum Cable Length

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Total Channel Length

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Max Patch Cable Length

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Voltage Drop

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Delivered Voltage

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Power Loss

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Results Table

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Frequently Asked Questions

What is the maximum length for Cat 6 ethernet cable?

The maximum channel length for Cat 6 ethernet cable is 100 meters total, including horizontal runs and patch cables. This follows the IEEE 802.3 standard for structured cabling systems.

How does cable gauge affect ethernet cable length?

Thicker cable gauges (lower AWG numbers) have less resistance and allow for longer patch cable runs. For example, 24 AWG allows longer patch cables than 26 or 28 AWG while maintaining the 100m total channel limit.

What is the difference between horizontal and patch cable length?

Horizontal cable is the permanent installation run between wall outlets and patch panels. Patch cables are the flexible jumper cables connecting devices to wall outlets or patch panels.

How does PoE affect maximum cable length?

PoE introduces voltage drop due to cable resistance, which can limit effective cable length. Higher power requirements and longer distances result in greater voltage drop, potentially requiring shorter cables or higher input voltages.

What voltage drop is acceptable for PoE applications?

Most PoE devices can operate with input voltages between 37-57V. The acceptable voltage drop depends on your device specifications, but generally you want to maintain at least 37V at the device end.

Is Cat 6A better than Cat 6 for long runs?

Cat 6A has better performance characteristics and can support 10 Gigabit Ethernet over the full 100m distance, while Cat 6 is limited to shorter distances for 10GbE. For standard Gigabit Ethernet, both perform similarly.

How do I calculate power loss in ethernet cables?

Power loss is calculated using the formula P = I²R, where I is current and R is cable resistance. Higher currents (more power) and longer cables result in greater power loss and voltage drop.

What factors affect ethernet cable resistance?

Cable resistance is affected by wire gauge (AWG), cable length, temperature, and cable quality. Thicker wires have lower resistance, and resistance increases with length and temperature.