Four names, four sets of limits, and a quote sheet that lists all four with different prices against each. The whole ladder fits on one page, and once you have seen it side by side the procurement conversation gets much shorter.
Figure 1: Modern networking portfolio spanning Category 5 through Category 6A standards.Quick answer
| Cat5 | Cat5e | Cat6 | Cat6A |
|---|
Bandwidth | 100 MHz | 100 MHz | 250 MHz | 500 MHz |
|---|
1G to 100 m | Yes | Yes | Yes | Yes |
|---|
2.5GBASE-T | Not specified | 100 m | 100 m | 100 m |
|---|
5GBASE-T | Not specified | Not specified | 100 m | 100 m |
|---|
10GBASE-T | Not specified | Not specified | 55 m | 100 m |
|---|
Typical conductor | 24 AWG | 24 AWG | 23 AWG | 23 AWG, often larger |
|---|
Pair separator | No | No | Usually a spline | Spline, tighter geometry |
|---|
ISO/IEC class | Withdrawn | D | E | EA |
|---|
Listed in the current TIA-568.2-D | No | Yes | Yes | Yes |
|---|
The one column that decides most projects
10GBASE-T distance.
Everything else in that table is background. If the design needs 10-Gigabit to the desktop, Cat5e and Cat6 are both out at building distances and the choice collapses to Cat6A. If the design needs 1G to the desk with an option to move later, Cat6 covers the full 100 meters at 1G, 2.5G and 5G, and reaches 10G on runs under 55 meters. If the tenant is content at 1G for the life of the fit-out, Cat5e is the cheapest thing that is still a recognized category.
What each step actually changed
Cat5 to Cat5e: nothing in the bandwidth, everything in the limits. Both are 100 MHz. What changed was the crosstalk and return-loss figures — tightened so that four-pair, bidirectional Gigabit transmission would have margin instead of luck.
Cat5e to Cat6: a real increase in bandwidth, plus a physical change. The ceiling went from 100 MHz to 250 MHz, and the cable grew a spline separating the pairs, with 23 AWG conductors in place of 24 AWG. That combination is what opens up 5G over the full channel and 10G over short runs.
Cat6 to Cat6A: more of the same, taken further. 500 MHz, tighter alien-crosstalk limits for cables lying alongside each other in a bundle, and larger conductor geometry to hold the tolerances. The result is 10GBASE-T over the complete 100-meter channel instead of 55.
Where the four land against the ISO classes
The TIA categories and the ISO/IEC 11801 classes are two naming systems covering the same physical performance. Class D corresponds to Cat5e, Class E to Cat6, Class EA to Cat6A. A European tender written in classes and a US tender written in categories can specify the same cable and still look like two different documents. If you are reconciling the two, the class ladder is set out in full on our ISO 11801 class guide.
Reading a quote with four line items
Run type | Sensible pick | Reasoning |
|---|
Office desk, 1G target, longest run 60 m | Cat6 | Full margin at every rate up to 5G, and 10G stays available |
|---|
Office desk, 10GBASE-T specified, longest run 75 m | Cat6A | Cat6 cannot meet the requirement at that length |
|---|
Access point uplink on 2.5G | Cat6 | 2.5G runs the full channel; Cat6A buys nothing here |
|---|
Legacy phone or printer drop, 1G only | Cat5e | Cheapest recognized category that meets the job |
|---|
Dense bundle in a shared pathway, 10G later | Cat6A | Alien crosstalk between cables is the design constraint, not pair crosstalk |
|---|
The pattern is that the top row of that table covers most of the building, and the exceptional rows are what the specification is actually for. A quote that lists four line items is not usually asking you to choose one — it is asking you to allocate them.
The channel is 100 meters, and it is not all permanent link
Every distance in the table above is a channel figure: up to 90 meters of permanent link plus up to 10 meters of patch cordage. When somebody tells you their runs are 95 meters, ask whether that is the permanent link or the end-to-end channel. The distinction is the difference between a compliant installation and a link that passes on a cool day.
What a category label does not tell you
A category printed on a jacket is a minimum, not a promise about installed performance. Cat6A cable pulled around a tight corner, bundled forty deep in a riser, or landed on a patch panel that was never rated for it will fail certification even though the reel was perfect. Three things do more damage to a channel than the category choice does:
- Bend radius. Keep the cable above four times its outer diameter through the pull and at every termination point.
- Untwisted length at the termination. The margin lives in the twist. Every extra millimeter of untwisted pair at a jack is margin removed, at the exact point where the link is already weakest.
- The lowest-rated component in the channel. Cat6A cable run into a Cat6 panel with Cat5e patch leads performs as Cat5e. The label that governs certification is the one on the weakest item.
That is why a certification report says more than a parts list. It measures the assembled channel rather than the sum of its datasheets.
Three jobs, three answers
A school district re-cabling 400 drops to 1G with a five-year horizon. Cat6. It carries 1G and 2.5G over the full channel, and it keeps 10G available on the shorter runs without a second re-cable.
A design studio specifying 10GBASE-T to every edit seat, longest run 68 meters. Cat6A. At that distance the requirement is not negotiable, and a Cat6 substitution would fail certification on the longest runs.
A landlord refreshing a suite for a tenant who asked for "the cheapest that works". Cat5e on the short drops, Cat6 on the long ones. Splitting the quote is legitimate as long as the channel lengths are known, the standard’s minimum grade is respected, and the two grades are labeled differently at the panel so nobody has to guess later.
FAQ
Is Cat6A worth it over Cat6?
Only against a requirement. If 10GBASE-T must reach 100 meters, or alien crosstalk in a dense bundle is a design constraint, it is not optional. Otherwise Cat6 meets the job and Cat6A is headroom.
Can I put Cat5e, Cat6 and Cat6A in the same installation?
Yes. Each channel performs to its own weakest component. Certification is done channel by channel, so label the grades differently at the panel to avoid confusion later.
Does Cat6 use the same connectors as Cat5e?
Yes, the RJ45 interface and the T568 wiring assignment are the same across all four. The difference is in the cable and in what the components are rated for.
Why does Cat6 only reach 55 meters at 10G?
Because 250 MHz of bandwidth is not wide enough to hold the 10GBASE-T signal over the full channel. The limit is a property of the specified bandwidth, not of the manufacturing quality.
Do I need Cat7 or Cat8 if I am already considering Cat6A?
Only for a specific requirement. Cat7 is specified with a non-RJ45 interface, and Cat8 is a 30-meter channel intended for switch-to-switch links inside a rack row.
What about 2.5G and 5G?
They sit between 1G and 10G and run over Cat5e and Cat6 respectively at the full 100 meters. For access points, this is often the rate that matters, and it is cheaper to satisfy than 10G.
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