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Color Code (T568 / Fiber)

Visual reference of the T568A / T568B pinout (straight and crossover cable, with the pair that swaps) and the TIA-598-C fiber color code by strand number. To build and verify runs.

Reference

Straight = same standard on both ends. Crossover = A on one end, B on the other.

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RJ45 pinout · straight T568B

PinEnd AEnd BPair

Standard A T568A
Standard B T568B
Notes · T568 and TIA-598-C fiber

A vs B Between T568A and T568B, pairs 2 (orange) and 3 (green) swap — that is pins 1, 2, 3 and 6. Pairs 1 (blue) and 4 (brown) stay the same.

Straight The same standard on both ends (today almost always T568B). Connects PC↔switch, switch↔router, etc.

Crossover One end T568A and the other T568B: it swaps Tx/Rx (pins 1↔3 and 2↔6). Joins like devices (PC↔PC, switch↔switch) without Auto-MDI-X.

Fiber TIA-598-C orders 12 strands by color: blue, orange, green, brown, slate, white, red, black, yellow, violet, rose, aqua. Strands 13–24 repeat those colors with a black tracer.

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How it works

This visual reference shows the RJ45 pinout for the two wiring schemes of the ANSI/TIA-568 standard: T568A and T568B. You can view a straight-through cable (same scheme on both ends, nowadays almost always T568B) or a crossover cable (T568A on one end and T568B on the other), with the pin-by-pin table for both ends, the pair each conductor belongs to, and highlighted rows where the schemes differ.

The second view covers the optical fiber color code from the TIA-598-C standard: the 12 colors in order (blue, orange, green, brown, slate, white, red, black, yellow, violet, rose and aqua), applying both to buffer tubes and to the strands inside each buffer. A slider lets you locate any strand from 1 to 24: strands 13 through 24 repeat the sequence with a black tracer.

Example: building a T568B straight-through cable

  1. Select Straight · T568B and order the conductors on both ends: white-orange, orange, white-green, blue, white-blue, green, white-brown, brown (pins 1 through 8).
  2. Check that both ends are identical: in a straight-through cable, pin 1 on one end connects to pin 1 on the other.
  3. If you needed a crossover, the tool shows that only the orange and green pairs change: pins 1, 2, 3 and 6 are swapped (1↔3 and 2↔6), which is the Tx/Rx cross.

Frequently asked questions

What is the difference between T568A and T568B?
Only pairs 2 (orange) and 3 (green) are swapped, that is pins 1, 2, 3 and 6; the blue and brown pairs stay the same. Electrically both schemes perform identically: what matters is using the same one across the whole installation. T568B is the most common in commercial installs; T568A is required by some US government contracts.
Are crossover cables still needed?
Almost never. Devices with Auto-MDI-X (practically every Gigabit switch and NIC for years now) detect and correct the cross on their own, so a straight-through cable works even between two switches. The crossover (T568A on one end, T568B on the other) remains for legacy equipment without that feature.
What color is fiber strand 7? And strand 19?
Per TIA-598-C, strand 7 is red. Strand 19 repeats the color of position 7 (19 − 12 = 7) but adds a black tracer to tell it apart. The same 12-color sequence also identifies the buffer tubes of a loose-tube cable: buffer 2 is orange, buffer 3 is green, and so on.
What happens if I accidentally mix T568A on one end and T568B on the other?
You get an accidental crossover cable. With Auto-MDI-X equipment it will probably still work, but on links with legacy hardware, demanding PoE or cabling certification the wire map will show as a fail. The right fix is to re-terminate one end so both use the same scheme.
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