Difference Between RJ12 and RJ45 (With Table)

The rj12 and rj45 are made of plastic material that is used for a connector. Cable and connectors play a tremendous part in our lives. We may keep on jumping on our Television now and then, and if we do not have a connector to connect cable with it, there is less left to enjoy at home on a joyful Sunday.

RJ is the short form of Registered Jack that allows telecommunications connections with their standardized physical networking interface. Both these connectors have modular connectors with a mini ribbon connector type. Both these connectors are used for different purpose with different applications.

RJ12 vs RJ45

The difference between the rj12 and rj45 is that the rj12 has a slot connector of six, and the rj45 has a slot connector of eight. It differs from how they are fitted and wired into and the number of wires used for the connection.

The rj12 is a connector with six slots of conductors and positioning used to connect phone lines. Even though this technology is still in place, it seems to be pushed out of business these days due to the increased use of mobile technology in developing nations. But apart from telecommunications, there are many larger places where the rj12 is used as a connector.

The rj45 is a connector with eight slots of conductors and positioning, usually used to connect large functioning networks. Each conductor in the rj45 varies with their different performance. The rj45 provides extra jabs for connecting with other connectors. It has the wiring of cat 5 as well as cat 6 wiring used. The rj45 can be easily wired to any kind of pin available out or even in any generic version structured cabling system.

Comparison Table Between RJ12 and RJ45

Parameters of comparisonRJ12RJ45
Physical characterThe appearance of the rj12 is in a long rectangular shape.The appearance of the rj45 is in a squarish shape.
ConfigurationThe rj12 has a 6 position as well 6 connector configuration type of connecting the cablesThe rj45 has an 8 position as well as an 8 connector configuration type of connecting the cables.
FunctionThe rj12 helps to connect many telecommunications to one line of the telephone for transmitting the data.The rj2 helps to connect large computer and Ethernet networking communications for transmitting the data.
Transmission propertyIt cannot deliver heavy transmissions.It can deliver heavy transmissions.
Wiring usedThe rj12 uses cat 3 as well as cat 5 types of wiring.The rj45 uses cat 5 as well as cat 6 types of wiring.
Ribbon connectionThe rj12 has specialized flattened ribbon cable connections, which is made of copper.The rj45 does not have any specialized ribbon connection as such.
Signals transmittedThey help in the transmission of data through analogue signals.They help in the transmission of data through digital signals.
sizeThe rj12 is about 9.65 millimetres long.The rj45 is about 11.65 millimetres long.

What is RJ12?

The connector rj12 is a jack connector that enjoins in connecting a central telephone system with a single telephone line through a circuit line. It’s called a 6p 6c connector. These six slots of the rj12 are used for connection and communication of the wires. The rj12 has specialized flattened ribbon cable connections.

This cable consists of six flat cables made of copper and transmits and receives the signals electrically through it. These ribbons are coded using different colours, including red, blue, green, yellow, black, and white. These are mainly used for connecting the cat three and cat five wirings used.

The rj12 has a build that holds it strong from the inside and out. It has a gold coat with copper pins attached to them. The only drawback of the rj12 connector is that it cannot handle excessive heavy transmissions of data.

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What is RJ45?

The connector rj45 is used for Ethernet networking commonly. It looks almost like a telephone jack but with a wider surface. Most of the time, all Ethernet cables are referred to as rj45 cables as the rj45 connectors are used to connect the wire cables. It consists of eight pins. That is, they have 8 different wires.

A person can observe this if he closely looks upon any Ethernet cable. Out of these eight wires, four have solid colours, and the other four is stripped. This is mainly used to connect Cat 5 and Cat 6 cables. The connector rj45 has a capacity to hold around eight wired at one go which makes it have a durable and robust build from the inside and out.

It has copper pins with a gold coating to prevent the wire from rusting due to exterior forces. The main feature of the rj45 connector is that it can transmit very high energy at a very high-speed.

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Main Differences Between RJ12 and RJ45

  1. The rj12 connector is rectangular in shape, whereas the rj45 connector is in square shape.
  2. The rj12 is a connector having six connectors as well as six positions, whereas the rj45 is a connector having eight connections as well as eight positions.
  3.  The rj12 is mainly used for connecting telephone lines, whereas the rj45 is mainly used for wiring a large number of networks.
  4.  The rj12 uses Cat 3 or a cat five types of wiring, whereas the rj45 uses Cat 5 or a cat 6 type of wiring for connecting the major lines.
  5.  The rj12 is a six slot-type connector, whereas the rj45 is an eight slot-type connector.


The rj12 and rj45 both have their differences in characteristics and purposes to be used as a connector. Still, the rj45 is usually said to be a bit broader than that of the rj12, which makes it long-lasting and helps transmit heavy radiation. The rj45 is for large networking at a higher speed, making it better than the rj12. Both look very similar and identical, having the same plastic rigidly covered in them. The rj12 and the rj45 both are totally crucial connectors when it comes to the transmission of data.


  1. http://support.itx.bg/ASROCK%20IPC/Jumper/IMB-370-L.pdf
  2. https://ieeexplore.ieee.org/abstract/document/8284683/

Last update on 2021-04-10 / Amazon Affiliate links / Images from Amazon Product Advertising API