T568A vs T568B: Which One Should I Choose?


As is known to all, the colored wires should be positioned correctly when terminating the network cable or your Ethernet cable cannot work. T568A and T568B are wiring standards set by ANSI (American National Standards Institute), TIA (Telecommunications Industry Association ), and EIA (Electronic Industries Association). And the standard name of T568A and T568B is TIA/EIA568A and TIA/EIA568B.

You may be confused about which wiring standard to choose when terminating an Ethernet cable for your home or office network. You're here in the right place.

Two Types of Ethernet Cables

Two types of Ethernet cables are widely used in networking transmission: straight-through cable and crossover cable. Straight-through cable has a single wiring standard and both ends of the RJ45 connector use the T568A wiring standard or T568B wiring standard; while crossover cable has one end of T568A and the other end of T568B.

t568a vs t568b

In the past, these two types of network cables were necessary as the network interface card cannot recognize the wire order of network cables and a crossover cable was necessary when you need to connect the two same devices. For example, a crossover cable is used to connect a computer to a computer, a router to a router, and a switch to a switch.

But nowadays, it is recommended to use the same wiring schemes at both ends of the RJ45 connector. With the development of Auto MDI-X technology, the network equipment can automatically recognize whether the other device is the same and almost all users choose straight-through cable.

So, do you know what is T568A and T568B as well as the difference between them? The following will help you know more information about T568A and T568B so that you will further know how to choose them.

T568A vs T568B: The Similarity

Both T568A and T568B are used to offer a wiring scheme for terminating CAT cables to RJ45 connectors. Usually, an RJ45 connector has 8 positions, which means that the data transmission needs 8 conductors and they are generally twisted into 4 pairs. And the four main colors of T568A or T568B wiring standard are green, orange, blue, and brown.

T568A vs T568B: The Difference

Different Color Order

You can see from the RJ45 wiring diagram that the obvious difference between T568A and T568B is the switching of green and orange pin positions.

 Pin 1 2 3 4 5 6 7 8
T568A white/green green white/orange blue white/blue orange white/brown brown
T568B white/orange orange white/green blue white/blue green white/brown brown

t568a vs t568b

Different Backward Compatibility

T568A wiring scheme is compatible with one pair or two pairs of USOC wiring schemes, while T568B is only compatible with a pair of USOC wiring schemes. But T568B wiring standard can also match the AT&T 258A color code.

Different Application

T568A wiring scheme is used to interconnect dual computers and T568B is used to connect switches, HUBs, and other devices.

The Importance of Using RJ45 Wiring Standards

The test data shows that the network cable using the standard color order has a dense strand and the signal attenuation during the transmission won't be reduced. What's more, the transmission distance of the network cable can also be relatively long. But if you don’t use the standard color order, it may cause data loss or even interruption over long distance. So, you should definitely use the wiring standard of T568A or T568B.

A Brief Guide to Choose T568A or T568B

Different Scenarios

  1. In commercial applications, T568B has widespread use in telecom installation. But if you have old technology such as old fax devices or phones, T568A is recommended for you for its powerful backward compatibility.
  2. If you have the project guideline, please follow the recommended wiring scheme.
  3. If you need to upgrade or expand the current network, continue to use the same wiring scheme

In fact, T568A and T568B have subtle differences and one is no better than the other. All you need to do is to choose one, and then stick with it! But if you are hesitating about it, I recommend you to use the T568B wiring standard.

T568B Wiring Standard

ANSI/TIA recommended T568A in the past as the wiring diagram is compatible with old devices. But T568B has been more recommended nowadays and adopted by most people. On the one hand, the network equipment and terminal connection are generally using the T568B wiring standard; on the other hand, T568B is more cost-effective.


RJ45 Wire Diagram for T568B

 RJ45 Pin Wire Color 10Base-T Signal 100Base-TX Signal 1000Base-T Signal
1 white/orange Transmit + Transmit + BI_DA+ (TX+)
2 orange Transmit – Transmit – BI_DA- (TX-)
3 white/green Receive + Receive + BI_DB+ (RX+)
4 blue Unused Unused BI_DC+
5 white/blue Unused Unused BI_DC-
6 green Receive – Receive – BI_DB- (RX-)
7 white/brown Unused Unused BI_DD+
8 brown Unused Unused BI_DD-

T568B wiring scheme has been widely used in different scenarios and is popular among users as it can be compatible with AT&T 258A color code and it also meets the current and future needs.

RJ45 Connectors, Patch Panels, and Keystone Jack Color Code

Some of our customers found that the keystone jack color code differed from the RJ45 connector color code, and you may be confused about whether RJ45 connectors, keystone jacks, and patch panels use the same wiring diagram. There may be different ways to label the wiring diagram, and the color can also be arranged differently. But all of them use T568A/T568B wiring standards.

You need to follow the wiring diagram for standard RJ45 connectors and patch panels. For keystone jacks and some field termination plugs, you should wire your Ethernet cable according to the color sequence on the product itself.

keystone jack and special rj45 connector color sequence

What's the Difference Between T568A and T568B?

Watch on YouTube: "Sample output of devtools-to-video cli tool"

How to Make A Cat6 T568B Network Cable?

Step 1: First of all, put the strain relief boot through the cable or you need to make your cable again.

step 1

Step 2: Cut off the cable jacket by a wire stripper.

step 2 

Step 3: Use the cable jacket to make wires straight and arrange them in T568B wiring diagram.

step 3

Step 4: Check it again to see if the color order is right.

step 4

Step 5: Cut wires. Here is the tip: cut wires in an angled direction, which will make wires easy to pass through the connector.

step 5

Step 6: Insert the RJ45 connector into the cable.

step 6

Step 7: Crimp the RJ45 connector with a high-quality RJ45 crimping tool.

step 7

Step 8: Make the other end in the same way.

step 8

Step 9: Use the RJ45 tester to test whether the Ethernet cable can work well.

step 9


What happens if you mix T568A and T568B?

Never mix T568A and T568B. If you mix them, it will cause troublesome errors.

How do I know which one should I use?

If a new network is about to be built up, you're free to choose any type of wiring scheme according to your own needs. But if there is already a network infrastructure, you should make an effort to find out which wiring scheme was used and update the network within the original standard.

Is there a speed difference between T568A and T568B?

No, the only difference between T568A and T568B is the change of green and orange color codes.

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