RJ45 vs CAT5

RJ45 vs. CAT5

If you are wondering what these are? RJ45 and CAT5 are the names of two different connectors commonly used in networking. These are the two most commonly used terms in cable technology.

These are two different types and shapes of cable connectors, which have entirely different functions. Let’s know what each of them is used for.


RJ in RJ45 stands for Registered Jack, and 45 stands for an interface standard. It looks a lot like RJ11, the interconnection standard we used to find in our landlines usually. RJ45 is a wider version of the same and is predominantly used in computer networking now.

RJ45 has eight pins in it, so it is termed as a connector of 8 positions 8 contacts (8P8C) modular plug and jack. This connector is used to connect computers in an Ethernet-based LAN setting.

But what is RJ? The Registered Jack or the RJ is a standard telecommunication network interface to connect long-distance carrier service with voice and data equipment.

The RJ45 plus is made of plastic with 8 pins in the port. Four of these 8 pins are used to receive and send the data, while the other four other power networking devices and technologies.

The RJ45 comes with two color wiring schemes, namely T568A and T568B. Each of these wiring schemes follows different color schemes, each of which is important for different electrical compatibility. The wiring scheme acts as a means to terminate the cable onto the connector interface.

The most common of both is the T568A wiring scheme. If both the ends of the cords are wired with the same standard, it is a straight-through connection. In this case, both ends can function with the same wiring scheme i.e., T568A. However, if it’s a crossover connection, both the wiring schemes are used with each one at other ends. Such crossover connections are used in computer to computer networking where no router, switch, or hub is available.


CAT5, on the other hand, refers to category 5 cable. It is also a type of twisted pair cable used in computer networking. There are various types of Ethernet cables that are used to terminate with RJ45 connectors. CAT5 is one of them.

Depending on the speed that needs to be transmitted along the cable line, the RJ45 connector uses different category cables. A CAT5 cable is used to transmit 100MHz frequencies with a line speed of 100Mbit per second.

A CAT5 cable uses two twisted color-coded pair cables with a maximum range of 100 meters. Later, CAT5e was introduced for better specifications and standards. When used together, CAT5 and CAT5e are capable of transmitting Ethernet speed in Gigabit. The CAT5 cable is twisted to reduce crosstalk and for canceling EMI.

Apart from this, there are category 6 and category 7 cables as well that are capable of transmitting even more rated speeds as per the requirements. With the need to increase network speeds and match up with the upcoming future technologies, CAT5 cables are being slowly replaced by its advanced cable categories like CAT6 and CAT7.

Image Credit: amazon.com

The Difference Between RJ45 And CAT5

So, RJ45 and CAT5 are entirely different with different functions in computer networking. While RJ45 is used as a connector to cable wires, CAT5 is just a cabling device that determines the size of the bandwidth, i.e., the maximum speed the cables can transmit and be used for.


RJ45 doesn’t require any replacement and is even hard to replace, CAT5 has already been replaced by its higher and advanced category cables in most of the world for the need to transmit data with more speed than CAT5 can support.


RJ45 is easy to install with its plug and play style, which is why they were used as the replacement of RJ11 used ion old telephone connections with hardwired cords. CAT5 cable to be installed have to be looked out for the length of the wiring needed. CAT5 is suitable for only 100 meters long connection.

Advanced Version

CAT5 is also considered an obsolete cable, as is not preferred if your office or home is switching to advanced networking. In the long term, CAT6 matches better speed requirements and proves to be cost-effective than CAT5 cable.

On the other hand, RJ45 is already the best connector and has fully replaced its predecessor, RJ11. RJ45 is more suitably used in more applications like telecommunications, Ethernet, factory automation. It is also used for networking devices like modem, computers, laptops, ethernet cables, printers tec.


The category of cables comes under RJ45. Therefore, RJ45 is a wider concept than CAT5, which forms a small part of the RJ45 connector.


RJ45 is a device with 8 pins and 8 different color-coordinated wires with a plastic body. CAT5 cable, on the other hand, is a device with 4 twisted color-coded cable that has a maximum length of 100 meters only.

Jack vs plug

A jack is a fixed part of the connection, whereas a plug is what is inserted in the jack. The plug fixed at the end part of the cable. RJ45 is the jack used in the Ethernet network that is meant to be fixed, whereas CAT5 is the plug inserted in RJ45 jacks to fulfill an Ethernet connection.

This was all about RJ45 and CAT5. If you are looking out for a new Ethernet connection in your office and home, make sure the connection uses a category cable that is above CAT5 to experience faster internet speed. One should no longer consider CAT5 cables for new connections. You should opt for CAT5e and above to handle network traffic well.

If you are a well-established business with a number of computers and servers, opt for category 6 cable or above. It is more affordable, provides better speed with a reduced cable distance. In CAT6a, you will enjoy double frequency with a reduction in noise interference and 10 Gigabit speed.

Levi Alston is a student at the University of Illinois Urbana-Champaign. He is currently studying computer science, and he plans to minor in business. Levi enjoys spending his free time on PC and internet forums, where he can talk about anything and everything with friends. He is a witty guy with a friendly demeanor, and he loves making people laugh.