Are RJ45 and Cat6 The Same?

Ethernet cables are essential components of Ethernet networks. They’re not only made up of cables alone; at both ends of the cable are the RJ45 connectors. They work hand-in-hand, and it’s impossible to use one without the other. Once fused, the cables that they form become the nerves of the network, allowing data transmission between the devices. The cables are commonly named after the cable category, but they’re also referred to as RJ45 cable. Nowadays, Cat6 cables are the most common Ethernet cable due to the rise of Gigabit Ethernet. Although Cat6 and RJ45 do not refer to the same thing, there are still times that they are used interchangeably, raising confusion and sometimes even arguments as to what these two things really are. It’s simple to differentiate between the two if you’re in the networking space, but for those who are still novices or for those who are simply curious, this article will delve into these things to shed some light on your confused minds.

What is Cat6?

Ethernet cable comes in different types and sizes. There are the traditional twisted-pair cables and the much faster fiber optic cables. The most commonly used is still the twisted pair cable because they are cheaper and, in small-scale networks, are more practical to use than fiber optics cables. These cables are made up of four twisted pairs of insulated copper wires. Twisted pairs have been around since the early Ethernet days, and many iterations have been made to adapt to the increasing internet speed. Twisted pair cables are classified into categories. Starting with Cat1 in the 1970s, the Ethernet cable has evolved to Cat7, which has the highest bandwidth and speed among the cable categories. Lower categories of cables such as Cat5 and Cat6 are still in use today because there are existing Ethernet standards where they are more fit to use than the latest Cat7.

Cat6 or Category 6 cable has higher bandwidth and higher transfer rates than the previous iterations and was developed for Gigabit Ethernet. Still, it can also be used for video and telephone applications. Cat6 has a bandwidth capacity of 250MHz and offers a speed of up to 10Gbps. It’s also backward compatible with fast Ethernet standards 10BASE-T and 100BASE-TX and with lower cable categories such as Cat5/5E and Cat3. Cat6 can support Gigabit ethernet at up to 100m; beyond this, the connection will begin to slow down or, in some cases, will be completely lost. The distance is further reduced to 55m for the 10Gigabit Ethernet standard. Repeaters are normally used for undisrupted connections in longer distances.

Cat6 cables also improved on the crosstalk issue experienced by previous cable categories. Crosstalks are electromagnetic interferences or disturbances that form up when the cables are adjacent to one another, affecting the signal’s quality. Cat6 uses better insulation materials to reduce the noise level, maintain data integrity and provide uninterrupted, high-speed performance.

What is RJ45?

RJ45 is the standardized networking interface primarily used for Ethernet cables. In simpler terms, it’s the plastic connector you often see on both ends of Ethernet cables, such as the Cat6 cable. If you’re wondering why it’s called “RJ45”, the RJ stands for “registered jack,” and 45 is the number of the interface standard. The correct technical term is 8P8C (8 pins/8 conductors) RJ45 Ethernet connector, where 8P8C refers to the 8 pins and 8 conductors for each of the wires in twisted pair cables.

We mostly see RJ45 connectors in Ethernet networks, but did you know that it wasn’t originally built for that purpose? RJ45 connectors were first built for telephone communications. They were used to connect modems to telephones. The standard was later on adapted to computer networks and is now widely used in Ethernet networks. Nowadays, most, if not all, networking devices are compatible with the RJ45 cable connection. You normally see cables with RJ45 connectors plugged into the Ethernet port of your computer. Still, it is also the same connection used in printers, modems, network storage devices, IoTs, and many other networking devices.

RJ45 connectors all look the same externally to fit into the standard RJ45 port, but that is not always the case when you look on the inside. There are a few things to consider when choosing the right RJ45 connector. For one, you have to know the cable jacket’s (OD) outside-diameter that the plug is capable of accepting. The conductor insulation diameter is another thing to consider. For example, in the case of Cat6, since it is a thicker cable, you have to choose an RJ45 plug that can accept the bigger outside-diameter and thicker, insulated, copper-conductor diameter of the cable. Aside from this, you also have to know if the plug you need is 2-prong or 3-prong. 3-prong plugs are suitable for stranded and solid copper conductors, while 2-prong plugs are suitable for stranded copper only. Lastly, you need to find out whether you need an unshielded or a shielded RJ45 connector. There won’t be any issues if you use a shielded connector with an unshielded cable, but you can only use a shielded connector with a shielded cable for the ground and shield to function properly.

No, They’re Not the Same!

Much of the confusion between RJ45 and Cat6 stems from those referring to Cat6 cables as RJ45 cables too. Adding to the confusion is the wrong labeling of RJ45 cable bags by some manufacturers. They would normally indicate the category number of cables, like Cat6, outside the bag of RJ45 connectors even though they’re not category-specific at all.

Based on what was discussed in this article, it is now safe to say that RJ45 and Cat6 are two very different networking pieces. Aside from the fact that they are both used in Ethernet networking, they don’t share any other similarities. Both are fundamental components of a network since they make up the Ethernet cable which is the primary communication pathway between network devices. Although both need to work together to connect two devices in a network, they are not the same.

About the author

Glynis Navarrete

A freelance blogger who loves to write about anything related to technology. Born and raised in the Philippines and worked in Singapore for eight years as Technical Support for a wide range of IT equipment. Took a dive into the world of freelancing and now enjoying doing what I’m passionate about while not losing touch with technology.