Ethernet cables look almost identical from the outside, but the category printed on the jacket makes a significant difference to your network’s performance and future-proofing. Here’s what each type means and how to choose the right one.
Why Ethernet Cable Category Matters
Each cable category (Cat) defines the cable’s construction, the frequency it can carry, and the maximum speed it supports over a given distance. Choosing the wrong category for your environment means either overspending on capability you don’t need, or installing cabling that becomes a bottleneck within a few years.
Since structured cabling is typically installed inside walls and ceilings and replacing it later is expensive and disruptive, it’s worth getting right the first time.
The Main Categories
Cat5e (Category 5 Enhanced)
- Max speed: 1 Gbps
- Max frequency: 100 MHz
- Typical use: Older office installations, basic home networking
Cat5e was the standard for many years and is still found in a large number of existing business premises. It handles 1 Gbps reliably over up to 100 metres, which is fine for most current needs. However, it doesn’t support the 2.5 Gbps or 10 Gbps speeds that are becoming more common in modern switches and devices.
If you’re replacing or extending an existing Cat5e installation, it’s generally worth upgrading to Cat6 or Cat6a rather than matching the old standard.
Cat6 (Category 6)
- Max speed: 10 Gbps (up to 55 metres), 1 Gbps (up to 100 metres)
- Max frequency: 250 MHz
- Typical use: New office installations, modern small business networks
Cat6 is currently the most common choice for new business installations. It supports 10 Gbps over shorter runs, which is useful for server room connections and high-speed uplinks, while still delivering solid 1 Gbps performance across a full 100-metre run.
Cat6 cables are slightly thicker than Cat5e and include a spline (an internal separator) that reduces crosstalk between the wire pairs inside.
Cat6a (Category 6 Augmented)
- Max speed: 10 Gbps (up to 100 metres)
- Max frequency: 500 MHz
- Typical use: Server rooms, data centres, future-proof office infrastructure
Cat6a extends 10 Gbps performance to the full 100-metre standard run length, rather than the 55-metre limit of Cat6. It’s noticeably thicker and less flexible than Cat6, which makes it more difficult to route in tight spaces, but it’s the right choice when you need sustained 10 Gbps across longer distances.
For a new office installation where you want the cabling to last 10–15 years without becoming a constraint, Cat6a is worth the modest additional cost.
Cat7 (Category 7)
- Max speed: 10 Gbps
- Max frequency: 600 MHz
- Typical use: Specialist and data centre environments
Cat7 requires shielding on every individual pair inside the cable, as well as an overall shield, making it significantly more expensive, stiffer, and harder to terminate. It also uses a non-standard connector (GG45 or TERA) rather than the standard RJ45, which creates compatibility issues with most networking hardware.
Cat7 is rarely recommended for standard business environments. If you need 10 Gbps performance at full run lengths, Cat6a achieves the same result with standard connectors and better real-world compatibility.
Cat8 (Category 8)
- Max speed: 25–40 Gbps
- Max frequency: 2,000 MHz
- Typical use: Data centres, server-to-switch connections over short distances
Cat8 is designed for very short runs (up to 30 metres) at extremely high speeds. It’s a data centre cable, not an office cable. For most SMEs, it has no practical application outside of connecting servers directly to top-of-rack switches.
Shielded vs Unshielded
Ethernet cables come in two shielding variants:
- UTP (Unshielded Twisted Pair): No additional shielding around the wire pairs. Works well in most office environments where electrical interference is not a major concern.
- STP / FTP / S/FTP (Shielded): Individual pairs or the overall cable are wrapped in foil or braid shielding. Required in environments with significant electromagnetic interference, near heavy machinery, fluorescent lighting, or industrial equipment.
Shielded cables require compatible (shielded) connectors and patch panels, and must be properly earthed to be effective. If earthing is done incorrectly, shielded cable can actually perform worse than unshielded. For most office environments, good quality UTP is the right choice.
Which Cable Should Your Business Use?
| Scenario | Recommended Category |
|---|---|
| Replacing or patching an existing Cat5e install | Cat6 minimum |
| New office or fit-out | Cat6a |
| Server room uplinks | Cat6a |
| Industrial or high-interference environment | Cat6a STP or Cat6 STP |
| Data centre, server-to-switch (short runs) | Cat8 |
| General patch cables (desk to wall) | Cat6 |
A Note on Patch Cables vs Structured Cabling
There are two contexts where cable category matters:
Structured cabling is the permanent installation inside your walls, ceiling, and cable trays, the runs from your comms cabinet to wall outlets. This is where category choice has the most impact and where it’s most expensive to change later.
Patch cables are the short cables you use to connect devices to wall outlets, or switches to patch panels. These are cheap and easy to replace. Using Cat6 patch cables on a Cat5e permanent installation won’t improve performance, the limiting factor is always the lowest category in the link.