Ethernet RJ45 Wiring
T568A / T568B wire order + straight-through/crossover — follow it when crimping a plug.
What it does: Look up the standard wire order and arrangement of the 8 conductors in an RJ45 cable.
When to use it: When crimping your own cable, building a network module, or troubleshooting wiring.
MEANS Same standard at both ends = straight-through cable (most common); A at one end and B at the other = crossover cable.
No history yet. Each calculation is automatically saved to this device.
How to use the RJ45 wiring reference
Choose a standard and arrange by wire color.
- 01
Choose a standard
Generally use T568B (the most common in North America). Both ends of the same cable must use the same standard.
- 02
Order the wires by color
Arrange the 8 conductors left to right (pins 1→8) per the table below and crimp them into the plug.
- 03
Straight-through or crossover
Modern equipment has Auto-MDIX, so almost everything uses a straight-through cable (T568B at both ends); a crossover cable (A at one end, B at the other) is basically no longer needed.
T568A vs T568B (only the orange/green pairs swap)
The two standards differ only in the position of the orange and green pairs; everything else is identical.
| Pin | T568B | T568A |
|---|---|---|
| 1 | White/Orange | White/Green |
| 2 | Orange | Green |
| 3 | White/Green | White/Orange |
| 4 | Blue | Blue |
| 5 | White/Blue | White/Blue |
| 6 | Green | Orange |
| 7 | White/Brown | White/Brown |
| 8 | Brown | Brown |
ANSI/TIA-568 standard.
Common questions, answered in 3 minutes
T568A or T568B?
They are functionally identical, so just pick one and use it consistently. North American projects mostly default to T568B; government/residential cabling codes sometimes require T568A.
Difference between straight-through and crossover cables?
Straight-through = same standard at both ends, for dissimilar devices like PC↔switch; crossover = A at one end and B at the other, for similar devices like PC↔PC. Modern ports support Auto-MDIX, so a straight-through cable works for everything.
Can 100 Mbps work with only 4 wires?
Yes. 100BASE-TX uses only 4 wires (two pairs): 1/2/3/6; but Gigabit 1000BASE-T must use all 8 wires, so it is recommended to always crimp all 8.
What if I cannot remember the wire colors?
Remember the T568B order: 1 white-orange, 2 orange, 3 white-green, 4 blue, 5 white-blue, 6 green, 7 white-brown, 8 brown.
Standards and sources referenced by this tool
| Item | Value / Formula | Source |
|---|---|---|
| T568A / T568B wire order | 8 conductors, orange/green swapped | ANSI/TIA-568 |
Wire order comes from ANSI/TIA-568, no external API.