LAN Wiring (T568A / T568B)
This RJ45 pinout chart shows the wire-color order and signal assignment for both T568A and T568B. Use the same scheme at both ends for a straight-through cable; use different schemes only when a crossover cable is required.
RJ45 8-pin color code| Pin | T568A | T568B | 10/100 signal |
|---|
| 1 | White/Green | White/Orange | TX+ (transmit) |
| 2 | Green | Orange | TX− |
| 3 | White/Orange | White/Green | RX+ (receive) |
| 4 | Blue | Blue | — (unused) |
| 5 | White/Blue | White/Blue | — |
| 6 | Orange | Green | RX− |
| 7 | White/Brown | White/Brown | — |
| 8 | Brown | Brown | — |
Straight-through and crossover| Cable type | Both ends | Use for |
|---|
| Straight-through | Same standard: B–B (or A–A) | Connect unlike devices: PC ↔ switch/hub, switch ↔ router. |
| Crossover | Different standards: one end A, one end B | Connect like devices without Auto-MDIX: PC ↔ PC, switch ↔ switch. |
Pin order and colors follow the TIA/EIA-568 standard (not JIS — Japan uses the same one). The structured cabling system (Cat5e/Cat6… classes and performance) is covered by JIS X 5150, Japan's adoption of ISO/IEC 11801. The signal column is for 10/100BASE-TX; Gigabit (1000BASE-T) uses all four pairs bidirectionally. Within one cable both ends must be crimped to the SAME standard (A–A or B–B) to make a straight-through cable. Most modern network gear has Auto-MDIX, so a straight-through cable works in the great majority of cases.
Frequently asked questions
What is the difference between T568A and T568B?
They swap the green and orange pairs, while the blue and brown pairs stay in place. Compare the two color columns in the chart before terminating each RJ45 pin.
Does a straight-through cable use T568A or T568B?
Either scheme works when both ends match. Follow the same T568A or T568B column at both ends and keep pins 1–8 in the listed order.
Does JIS X 5150 define the T568A/B color order?
The T568A/B color pinout comes from TIA-568; JIS X 5150 covers structured cabling systems. The chart names both so their scopes are not confused in project requirements.
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