Color-codes for rj45: An ultimate guide on RJ45 ethernet wiring colors

Choosing a suitable cable is hard, and figuring out its harness design is even more challenging. It requires a lot of practice to recreate the perfect setting. For that, the cable manufactures colored wires so that it is easy to connect and maintain them. Let’s find out the color codes for RJ45 and how to achieve it.

What are RJ 45 Connectors?

Ethernet networks use RJ45 connectors to transfer audio and video data. They are standard except for the highest-end Cat.8 networks, but it’s also used on Cat.1, Cat.6, and Cat5e networks.

Initially, they worked as a more compact and affordable replacement for traditional hardwired telephone setups. As a result of its plug-and-play nature, the setup is simplified. RJ45 is more flexible than its predecessor, RJ11, and may be utilized in more comprehensive situations, such as Ethernet networking, telephone, and factory automation. In most cases, people will use some combination of Ethernet connections, modems, personal computers, portable media players, and printers.

8 pins on the RJ 45 ports

Caption: 8 pins on the RJ 45 ports

About the Ethernet Cable

There are four pairs of wires in an ethernet cable.

Category 5 or above Unshielded Twisted Pair (UTP) ethernet cable is widely available in bulk from electronics retailers and home improvement stores. For 10/100 functioning, Cat 5 is necessary; for gigabit, Cat 5e is preferable; and for some degree of future-proofing, Cat 6 or higher is recommended. For more protection against outside interference, you can utilize STP (Shielded Twisted Pair).

Although there is a wide variety of bulk ethernet cables, they may be broadly classified into two groups: solid and braid stranded. Desktop patch applications benefit most from using stranded ethernet wire. It is simpler to operate, more flexible, and more durable than a solid Ethernet connection, but it is only helpful for wiring shorter distances. And you can use the Ethernet cable with solid conductors for permanent installations over extended distances. 

When running an Ethernet connection across a plenum or other air-handling facility, you must utilize a plenum-rated cable, for instance, underneath a raised floor or above a false ceiling. Identifying the sort of ethernet cable inside a package or from a label may be difficult or impossible. Therefore it’s best to remove one end and look inside.

Ethernet cable 

Caption: Ethernet cable 

RJ45 ethernet port color code

 It is common practice to utilize patch cords to connect computers and network hubs. T568A and T568B are the two different types of wiring standards. The more prevalent T568B standard and the less common T568A differ in how their wires are colored and organized. One key distinction is that the green and orange pairs of pins are reversed in orientation.

Color-codes for rj45: Functions of 8 Pins in RJ45 Port

Pins 1 and 2 in the RJ 45 port on your computer and router are for sending data; pins 3 and 6 are for receiving the data, and pins 4,5,7, and 8 are for the electrical supply for Point-of-ethernet devices.

However, the RJ45 ports on the hub or switch receive data from pins 1 and 2, transmit data from pins 3 and 6, and connect the power over Ethernet (PoE) devices through pins 4,5,7, and 8.

Color-codes for rj45: RJ45 Plug Termination

Uplink port transmitting and receiving pins 1 and 2 on 10BASE-T and 100BASE-T nodal devices like PCs and routers. However, hubs and switches use pins 3 and 6 for transmission and pins 1 and 2 for reception. For 1000BASE-T and higher speeds, you need all four pairs.

Connecting the transmitter to the receiver pin allows two networking devices to exchange data. 

Because of this, when we need to link two completely different gadgets, such as PC to PC, Switch to PC, Router to Switch, etc., we employ straight-through pinout patch cable terminations (both sides need to have the same connection criteria, either EIA/TIA 568A or EIA/TIA 568B).

However, connecting two similar devices, such as PC to PC, Switch to Switch, and Router to Router requires only a T568A termination at one end and a T568B termination at the other. Crossover cables are a common name for these kinds of patch connections. In many cases, current gadgets can detect when you connect them and initiate crossover transmission automatically.

Color-codes for rj45: RJ45 Jack Termination

The module’s internal wiring dictates the colors assigned to the jacks. Typically, jacks use lead frames (a single metal strip) or printed circuit boards (PCBs) to transmit signals from the cable or the jack’s rear to its contacts or pins.

Connectors with a color code indicate whether they are T568A or T568B so that you know the type while terminating the jack. Moreover, the jack color coding also varies; hence don’t forget to look over the label carefully. Different manufacturers, or even models of the same manufacturer’s connectors, may use different color codes.

Caption: the color code of the T568A standard

Caption: the color code of T-568B standard

Types of RJ45 Ethernet cable and RJ-45 wiring

There are many types of RJ45 Ethernet cables. Which type should you choose? In many cases, tradition influences the choice. Because of AT&T’s previous 258A color code, T568B is standard in America. Although you can use either T568A or B for cabling in new construction, it is essential to be consistent so that plugs and jacks align.

Color-codes for rj45: Straight-Through Cables

Straight-through cables have identical terminations on both ends, conforming to the EIA/TIA-568-A or B standards. Nowadays, most systems use the T568-B standard to terminate patch cables. However, you can use both standards in straight-through cables.

The standard for linking MDI and MDIX devices is a straight cable. Thus, you will connect the MDI and MDIX interfaces via a straight cable, even though they are very different devices. Additionally, 10Base-T and 100Base-T use two pairs of wires in a four-wire (UTP) line. On the other hand, 1000Base-T uses all eight wires in a quad-pair cable.

Color-codes for rj45: Crossover Cables

Cross cables link two devices with the same type of RJ45 Port, such as a personal computer (PC) to another PC, a switch to another switch, or a router.

For this purpose, we are using an RJ45 cable to link two devices with identical pin configurations. You have to link the sender pin with the reception pin for two devices to exchange data. So, as you make a cross connection, you’ll need to adhere to the EIA/TIA 568A regulation on one end and the EIA/TIA 568B specification on the other.

The color of the crossover cable makes it easy to identify the appropriate connectors. Following this logic, you will connect Pins 1 and 2 to Pins 3 and 6. On both ends of the cable, you’ll use the identical formula.

Color-codes for rj45: Rollover Cable

Using this cable, you can access the router or switch console on a Cisco device. A computer or laptop on one end, a network hub or switch on the other. The RJ45 connector on one end of this cable pairs up with a DB9 serial port on the other. 

Moreover, Pin1 on one end connects to Pin 8 on the other, making this type of cable known as a “rollover.” Following that, pin2 on one side links to pin 7 on the other, and so on.

The EIA/TIA 568A and 568B standards can be used to set up a rollover cable. Remember that the other side requires a full reversal of the color scheme, regardless of the criteria you choose. 

Moreover, the cable is not for sending or receiving data. It is only for configuring the router.

Color-codes for rj45: Loopback Cable

RJ45 loopback cables have a jack with four contacts and are best for loopback connections in Ethernet networks. In such cables, all eight contacts are used in a redirected or looped transmission in Gigabit Ethernet.

Ethernet connector pinout straight crossover

Caption: Ethernet connector pinout straight crossover

How to Build an Ethernet Cable?

Building an Ethernet cable is simple. Even while patch cords with factory-terminated plugs are widely available, it is not unusual for users to create patch cables in the field. Here we go.

  • Get the required length by pulling the cable off the reel and cutting it with wire scissors or cutters. You can connect RJ-45 connectors once the cable draws through the opening.
  • Remove the cable’s outer jacket, starting at one end, using a wire stripper or a knife. Make sure you don’t nick the wires, or you’ll have to start over.
  • Flatten the cable, separate the pairs, and rewire it, so the ends match up. Cut the wires so their ends are parallel and no more than 1/2 inch of wire remains. Create a flat surface between your forefinger and thumb and flatten the end.
  • Ensure the clip is facing down or away from you when holding the RJ-45 plug. Now, push the wires firmly into the connector. Also, be sure to connect the wires in the correct order. Hold the cable securely while you crimp the RJ-45 connector.
  • Verify that you have aligned the wires with the correct polarity and that the crimped link is not ready to unravel. You need to check the Ethernet cable if any of these are wrong.
Connecting Ethernet cable with hub

Caption: Connecting Ethernet cable with hub


After knowing the color codes for RJ45, you must have a clear picture of Ethernet Cable Types. Further, ethernet cable can be made in many configurations, be it straight or crossover, Cat 5e or cat 5, plenum-rated or riser-rated, and so on. Each configuration contributes to different functionality and usage. Here at Cloom, we offer wiring harness solutions so that you don’t have to worry about perfection.

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