SpecCalc Hub
Compare all eight 8P8C contact colours for T568A and T568B. The green and orange pairs exchange positions; blue and brown stay the same.
Jack front view, latch recess on the left. Pin 1 at the top, 8 at the bottom, matching the Fluke front-view orientation. Not the rear IDC termination.
Selected contact: —
| Contact | Signal | Function |
|---|---|---|
| 1–2 | White / green | |
| 1–2 | Green | |
| 3–6 | White / orange | |
| 4–5 | Blue | |
| 4–5 | White / blue | |
| 3–6 | Orange | |
| 7–8 | White / brown | |
| 7–8 | Brown |
Jack front view, latch recess on the left. Pin 1 at the top, 8 at the bottom, matching the Fluke front-view orientation. Not the rear IDC termination.
Selected contact: —
| Contact | Signal | Function |
|---|---|---|
| 1–2 | White / orange | |
| 1–2 | Orange | |
| 3–6 | White / green | |
| 4–5 | Blue | |
| 4–5 | White / blue | |
| 3–6 | Green | |
| 7–8 | White / brown | |
| 7–8 | Brown |
Contact references below do not establish viewing orientation. The mating face and wire side are mirror images. Match the exact plug/receptacle drawing before wiring; the diagram only groups functions.
Compare all eight 8P8C contact colours for T568A and T568B. The green and orange pairs exchange positions; blue and brown stay the same.
Compare T568A and T568B conductor order and preserve the twisted pairs 1–2, 3–6, 4–5 and 7–8.
T568A and T568B describe two standard pin assignments for 8P8C Ethernet-style terminations commonly called RJ45 in practice. The key difference is the pair order on certain pins, not the basic connector shape.
This page is useful when crimping patch leads, checking wall outlets or diagnosing why one cable end does not match the other.
Read contacts 1–8 using the table and the actual connector orientation. The twisted-pair contact groups are 1–2, 3–6, 4–5 and 7–8, not four consecutive adjacent pairs.
The page is structured as a practical reference: start with the visible table, diagram and labels, then compare them with the exact connector, device, enclosure or symbol set in front of you.
Use the listed sources to confirm revision, naming and application context. Similar labels can hide different electrical limits, pin functions or test conditions, so the page should be treated as a guided reference rather than a universal standard text.
In T568B, contacts 1/2 are white-orange/orange and 3/6 are white-green/green. In T568A those green and orange assignments swap. A-to-A or B-to-B maintains straight-through colour assignment; mixing A and B changes the pair mapping.
If both ends follow T568B in the same orientation, the cable is a standard straight-through patch lead. The reference helps confirm the pin and color order before you reach for a cable tester.
If one end is T568A and the other is T568B, the pair mapping changes. Historically that indicated a crossover-style behavior in certain contexts, so the mixed termination should be intentional rather than accidental.
The colour convention alone does not determine speed. Link performance depends on the cable category, connectors, termination quality, installation and equipment.
The pairs are 1–2, 3–6, 4–5 and 7–8. They are not four successive adjacent pairs. Use the same stated plug orientation when reading a numbered drawing.
No. Continuity alone can miss a split pair and does not measure insertion loss, crosstalk or category compliance. Use a suitable cable tester for the required link standard.
Not inherently. The important thing is consistency with the project or building standard.
No. It only helps with pin order and orientation.
Because reversing connector orientation makes a correct order appear mirrored.
Explanation updated: 2026-09-16
This calculator provides an estimate for informational purposes only. It is not a certified engineering design, electrical safety approval, or professional installation recommendation. Always verify final decisions with a qualified professional and applicable local codes.