How Long Can an Ethernet Cable Be?

Whether you want to wire your entire house or are just looking to run a cable to the next room, you are bound to wonder about Ethernet cable length limits, and whether you’re risking connection problems. Here's everything you need to know.

An Ethernet cable lets you physically connect your computer to the internet or a local area network. It includes copper wires to transmit an electric signal containing data packets from one end to another. But as the signal moves through copper, it degrades due to resistance. As a result, all Ethernet cables have a maximum distance limit.

If you run an Ethernet cable for a distance longer than its limit, you will notice a decrease in the connection speed. Sometimes, when the cable is way longer than the limit, you may even suffer a connection loss.

Ethernet cables are divided by their category, which defines their capabilities and features, including the data transfer speed. For example, the Category 5 (Cat-5) cables can support data transfer speeds of up to 100Mbps. Similarly, a Cat-5e cable can sustain speeds of up to 1000Mbps.

But despite their different capabilities, almost all Ethernet cables, regardless of their category, have the same maximum length of 100 meters for their rated speed. This is possible because the higher you go in terms of category, Ethernet cables have more stringent requirements, such as better shielding to reduce interference and more twists or a spline to reduce crosstalk. Additionally, thicker or lower gauge wires are used in higher category cables. As resistance is inversely proportional to the thickness of a conductor (copper in the case of Ethernet cables), thicker or lower gauge wires have less resistance than thinner wires.

The Monoprice Cat-5e cable is excellent for long Ethernet runs. It's available in a 250-feet size and it uses 24AWG pure copper wires.

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There are three major exceptions to the Ethernet cable length limit: Cat-6, Cat-7a, and Cat-8. Generally, though, you only have to worry about Cat-6. The Cat-7a cables are based on a proprietary standard, so you are unlikely to encounter them, and the Cat-8 cables are only used in data centers and other high-bandwidth enterprise setups.

While Cat-6 Ethernet cables can support 1Gbps data speeds up to 100 meters, they can only deliver 10Gbps speeds up to 37-55 meters (121-180 feet), depending on the alien crosstalk atmosphere. Alien crosstalk is the electromagnetic noise that occurs when an Ethernet cable runs alongside one or more other signal-carrying cables.

Cat-7a cables can only support 40Gbps speeds up to 50 meters but are suitable for 10Gbps up to 100 meters. Lastly, the Cat-8 cables have a maximum length of 30 meters for their rated speed.

This StarTech Cat-6 cable is a high-quality Ethernet cable that supports up to 10Gbps data transfer speeds.

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One more thing to remember about the length limit of Ethernet cables is that it refers to the entire length of the Ethernet channel. A channel is essentially the complete end-to-end connection of a cable from a router, hub, or switch to a device, such as a computer, gaming console, or TV. So if you use permanent links with female keystone jacks and patch cables, the total length of patch cables and the link can't be more than the limit. The same goes when using an Ethernet coupler to extend a cable's length.

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Ethernet cables may be limited to the maximum length of 100 meters, but it doesn't mean you have to limit the size of a network. You can use a network switch to extend the length of an Ethernet connection. It regenerates the data signal to help it travel longer distances.

Another solution is using Ethernet to Fiber converters. As optic fiber cables use glass strands and light to transmit the data signal, they are comparably less susceptible to signal degradation or attenuation than copper cables. So optic fiber cables can be miles long.

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While Ethernet cables have a maximum length, most regular consumers will never have to worry about it as their Ethernet cable run is unlikely to cross 10-20 meters. But if you have a huge property and are running Ethernet cables for long distances, it's essential to keep the length limits in mind to avoid any performance issues.