What is the T568B colour order?

Left to right (pins 1-8): white/orange, orange, white/green, blue, white/blue, green, white/brown, brown. T568B is the most common standard in North American homes and offices.

What is the difference between T568A and T568B?

They are electrically identical and reach the same speeds. The only difference is that the orange and green pairs are swapped. Use whichever you like, but use the same standard on both ends of a normal straight-through cable.

Do I need a crossover cable?

Almost never anymore. A crossover cable uses T568A on one end and T568B on the other. Modern equipment has Auto-MDIX, which adjusts automatically, so a standard straight-through cable works for connecting any two devices.

How do I hold the RJ45 plug to read the pins?

Hold the plug with the gold contacts facing you and the locking clip underneath (pointing away). Pin 1 is then on the left, and the wires run 1 through 8 from left to right.

Ethernet Termination Guide

The colour order for terminating an RJ45 plug, with fancy diagrams for both the T568A and T568B standards - plus when to use straight-through vs. crossover.

RJ45 wiring order

Hold the plug with the gold pins facing you and the clip underneath. Pin 1 is on the left.

Pin	Wire colour	Signal
1	White / Orange	Pair 2 (TX+ / D1+)
2	Orange	Pair 2 (TX- / D1-)
3	White / Green	Pair 3 (RX+ / D2+)
4	Blue	Pair 1 (D3+)
5	White / Blue	Pair 1 (D3-)
6	Green	Pair 3 (RX- / D2-)
7	White / Brown	Pair 4 (D4+)
8	Brown	Pair 4 (D4-)

Hold the plug with the gold pins facing you and the clip underneath. Pin 1 is on the left.

Pin	Wire colour	Signal
1	White / Green	Pair 2 (TX+ / D1+)
2	Green	Pair 2 (TX- / D1-)
3	White / Orange	Pair 3 (RX+ / D2+)
4	Blue	Pair 1 (D3+)
5	White / Blue	Pair 1 (D3-)
6	Orange	Pair 3 (RX- / D2-)
7	White / Brown	Pair 4 (D4+)
8	Brown	Pair 4 (D4-)

Tip: T568B is the most common choice in homes and offices in North America. Either standard works - just be consistent. The only difference is that the orange and green pairs swap places.

Straight-through

Same standard on both ends (B-to-B shown). This is what you want for almost every cable: PC to switch, router to access point, etc.

End A · T568B

End B · T568B

Crossover

T568A on one end, T568B on the other. Rarely needed today - modern gear has Auto-MDIX - but useful for linking two old devices directly.

End A · T568A

End B · T568B

How to terminate an Ethernet cable

Terminating a cable means attaching an RJ45 plug to a bare run of twisted-pair cable. You'll need the cable, RJ45 connectors (use pass-through plugs if you're new to it), a crimping tool, and ideally a cable tester. Here's the process:

Strip the jacket. Remove about 1 inch (25 mm) of the outer jacket without nicking the inner conductors.
Untwist and fan out the pairs. Separate the four twisted pairs and straighten each conductor.
Order the wires. Arrange them left to right in your chosen standard (T568B order: white/orange, orange, white/green, blue, white/blue, green, white/brown, brown).
Trim flush. Hold the wires flat and cut them to an even length, leaving about 1/2 inch (12-14 mm) so the jacket reaches inside the plug.
Insert into the plug. With the clip facing down and the gold pins up, slide all 8 wires in until they hit the front. Confirm the colour order through the clear plastic and that the jacket sits under the strain relief.
Crimp. Insert the plug into the crimper and squeeze firmly to seat the contacts and lock the strain relief.
Test. Use a cable tester to confirm all 8 pins map straight through (1-8 to 1-8) with no shorts or crossed wires.

T568A vs. T568B: which should I use?

Both standards are electrically identical and deliver the same speeds. The only difference is the position of the orange and green pairs. T568B is the most common in North American homes and offices, while T568A is common in government and residential installs and is the standard referenced for voice. Pick one and use it on both ends for a normal (straight-through) cable.

Straight-through vs. crossover

A straight-through cable uses the same standard on both ends and is what you use to connect a device to a switch or router. A crossover cable uses T568A on one end and T568B on the other, historically needed to connect two like devices (PC-to-PC, switch-to-switch) directly. Almost all modern equipment supports Auto-MDIX, which detects and corrects the connection automatically, so you rarely need a crossover cable anymore.

Once your cable is terminated and tested, see the Ethernet cable guide to make sure the category (Cat5e/Cat6/Cat6a) matches the speed you need.

Frequently asked questions

What is the T568B colour order?: Left to right (pins 1-8): white/orange, orange, white/green, blue, white/blue, green, white/brown, brown. T568B is the most common standard in North American homes and offices.
What is the difference between T568A and T568B?: They are electrically identical and reach the same speeds. The only difference is that the orange and green pairs are swapped. Use whichever you like, but use the same standard on both ends of a normal straight-through cable.
Do I need a crossover cable?: Almost never anymore. A crossover cable uses T568A on one end and T568B on the other. Modern equipment has Auto-MDIX, which adjusts automatically, so a standard straight-through cable works for connecting any two devices.
How do I hold the RJ45 plug to read the pins?: Hold the plug with the gold contacts facing you and the locking clip underneath (pointing away). Pin 1 is then on the left, and the wires run 1 through 8 from left to right.