The short answer
Cat6 is the workhorse category for office floors, retail fit-outs and homes: four twisted pairs of solid copper, usually unshielded, in a jacket a little over 6 mm across. Cat6A (augmented Category 6) is specified in the same TIA-568.2-D family but tested to a higher frequency range, and it is the category intended to carry 10GBASE-T across the full channel length. Cat6 can carry 10GBASE-T only over shorter runs, per the standard. Everything else that buyers notice, such as a thicker cable, heavier boxes, more shielded versions and a higher price per metre, follows from that extra headroom.
Both categories share one rule that matters more than the A: category cable requires solid copper conductors. A box printed Cat6 or Cat6A with copper-clad aluminium inside is not a category cable at all, whatever the print says. The CCA vs copper guide explains how to spot it.
What the reference Cat6 construction looks like
The reference Cat6 U/UTP construction on our LAN and coax cable page comes from public datasheets. It has eight solid bare copper conductors of about 0.555 to 0.58 mm (23 AWG), HDPE insulation of roughly 1 mm diameter, a cross filler separating the four pairs, and a PVC or LSZH jacket of about 0.50 to 0.56 mm. Overall diameter is about 6.0 to 6.2 mm and the cable weighs around 40 to 43 kg per kilometre. A 305 m box has a gross weight of roughly 13.5 to 14 kg, per datasheet.
The standards cited on those datasheets are ANSI/TIA-568.2-D Category 6 and ISO/IEC 11801 Class E. For EU building projects the jacket also carries a CPR class such as Eca or Cca, declared on the DoP for that specific model.
| Point | Cat6 | Cat6A |
|---|---|---|
| Standard | TIA-568.2-D Category 6; ISO/IEC 11801 Class E | TIA-568.2-D Category 6A; ISO/IEC 11801 class per datasheet |
| Tested frequency range | Base Category 6 range | Higher range, per the standard |
| 10GBASE-T | Shorter runs only, per the standard | Full channel length, per the standard |
| Common constructions | U/UTP with cross filler | U/UTP with larger jacket, or F/UTP and S/FTP |
| Overall diameter | About 6.0-6.2 mm (reference) | Larger; per datasheet, varies with shielding |
| Conductor | Solid copper, 23 AWG typical | Solid copper, gauge per datasheet |
| Packing | 305 m box or reel | 305 m box or reel; heavier, check carton strength |
Why Cat6A is thicker
The extra performance has to come from somewhere. At higher frequencies the main enemy is alien crosstalk, the noise one cable picks up from the cables next to it in a bundle. Unshielded Cat6A fights it with distance: a thicker jacket, sometimes a profiled jacket, and more spacing between pairs and between neighbouring cables. Shielded Cat6A fights it with foil, either an overall foil (F/UTP) or a braid plus foil on each pair (S/FTP), and can often be slimmer than unshielded Cat6A as a result. Exact diameters vary by construction and maker, so the desk quotes them from the plant's datasheet rather than from a category rule.
Diameter is not cosmetic. It sets how many cables fit in a tray, a conduit or a patch panel, and it sets the box weight and carton count in a shipment. A designer who swaps Cat6 for Cat6A late in a project often has to resize containment as well. Shielding choices are covered in more depth in UTP vs FTP vs S/FTP.
Which one to buy
Use the network plan, not the label, to decide:
- Homes, small offices and retail: Cat6 U/UTP covers most access-layer links and is the easiest to install and terminate.
- Wi-Fi access points, PoE-heavy floors and new commercial fit-outs: Cat6A is common where the owner wants 10GBASE-T headroom to the outlet or large PoE bundles. Conductor size matters for PoE, as PoE and conductor size explains.
- Data centres: copper is mostly for short in-row links; backbone and spine links usually run on fibre. See the data centre application page.
- Industrial and outdoor runs: choose by jacket first (PE for outdoor, LSZH for public buildings) and then by category.
Installation cost also differs. Cat6A is stiffer and larger, so installers need wider bend allowances, larger containment and more time per termination, and shielded versions add bonding at every panel. Those labour and containment costs often outweigh the difference in cable price per metre, which is why the decision should be made at design stage rather than on the purchase order. When a buyer is unsure, the desk asks for the switch and access point specification and the longest planned run, then recommends one category for the whole project instead of a mix that is hard to stock and harder to certify.
What to write on the RFQ
A Cat6 or Cat6A request that gives only the category leaves the supplier to choose the gauge, conductor metal, jacket and shielding, which is exactly where cheap offers cut corners. A complete brief states:
- Category and construction: for example Cat6 U/UTP or Cat6A F/UTP, to TIA-568.2-D.
- Conductor: solid copper, gauge (23 AWG for the reference Cat6), with conductor DC resistance on the test report.
- Jacket and fire class: PVC, LSZH or PE; CPR class on the DoP for EU projects or a CMR or CMP rating for US projects.
- Print and packing: sheath print text, 305 m box or reel, carton marks and pallet pattern.
- Quantity: boxes per colour and per category.
For Cat6, partner factories commonly list an MOQ of 50 to 100 boxes of 305 m, with a few accepting 10 boxes, and lead times from about 5 to 25 days up to roughly a month. Cat6A runs and shielded versions are confirmed case by case. All figures are confirmed in writing for each order; the MOQ and lead time page explains the ranges and the quote form collects the fields above.
Checks before the boxes ship
Before shipment the desk compares sample weight against the datasheet, checks conductor colour and diameter on a cut sample, and reviews the plant's conductor resistance and transmission test records against the ordered category. Box weight is a quick first screen: the reference Cat6 box sits around 13.5 to 14 kg gross, and a box that is far lighter deserves a closer look. Field certification of the installed link is a separate step, described in Cat6 cable testing.