T568A vs T568B are the two wiring standards defined by the TIA/EIA-568 specification for terminating Ethernet cables with RJ-45 connectors. Both are electrically equivalent the only difference is the arrangement of the wire pairs. Choosing the right one depends on your installation type and existing infrastructure.
T568A Pin-Out
| Pin | Color | Function |
|---|---|---|
| 1 | White/Green | TX+ |
| 2 | Green | TX− |
| 3 | White/Orange | RX+ |
| 4 | Blue | — |
| 5 | White/Blue | — |
| 6 | Orange | RX− |
| 7 | White/Brown | — |
| 8 | Brown | — |
T568B Pin-Out
| Pin | Color | Function |
|---|---|---|
| 1 | White/Orange | TX+ |
| 2 | Orange | TX− |
| 3 | White/Green | RX+ |
| 4 | Blue | — |
| 5 | White/Blue | — |
| 6 | Green | RX− |
| 7 | White/Brown | — |
| 8 | Brown | — |
Key Differences
| Feature | T568A | T568B |
|---|---|---|
| Pins 1–2 | Green pair | Orange pair |
| Pins 3, 6 | Orange pair | Green pair |
| Performance | Identical | Identical |
| Used in | Government, residential, international | Commercial, North American enterprise |
When to Use T568A
- U.S. government and federal installations (FCC Part 68 mandated)
- Residential home network cabling
- European and international deployments
- One end of a crossover cable
When to Use T568B
- Commercial and enterprise office cabling in North America
- Matching existing T568B infrastructure
- Both ends of a standard patch cable
Can You Mix Them?
On a patch cable, never mix T568A vs T568B on the same cable both ends must use the same standard. The only intentional exception is a crossover cable, which uses T568A on one end and T568B on the other to swap TX and RX pairs for direct device-to-device connections.
Conclusion
T568A vs T568B are functionally identical the choice is about convention and compliance. Use T568B for commercial work in North America, T568A for government or residential installs. Above all, be consistent throughout any single installation.
