Ethernet Cable Categories: Cat5e, Cat6 and Cat6a Explained

For gigabit and 2.5-gigabit home networks, Cat5e is enough on runs up to 100 meters, and Cat6 or Cat6a is the safer buy when you are running new cable you want to last. Cat6a matters when you want 10-gigabit Ethernet over long runs, since Cat6 is limited to shorter distances at that speed. Check the whole path too, because the slowest port, switch or cable sets the speed.

Cable shopping gets confusing fast. Listings stack category names, speeds, shielding and lengths, and each claim sounds like it matters. For a home or home-office network it mostly comes down to three questions: how fast are your ports, how long is the run, and is the cable going into a wall or just across a desk?

What the categories mean

A category rating describes how much signal bandwidth the cable is built to carry, measured in megahertz. According to Wikipedia’s article on Category 5 cable, Cat 5e is rated to 100 MHz and is suitable for most Ethernet over twisted pair, though it more commonly runs at gigabit speed. Wikipedia’s Category 6 cable article gives Cat 6 a rating up to 250 MHz and Cat 6a up to 500 MHz, twice Cat 6. Higher numbers mean more headroom, not a different plug: all three use the same connector.

Cat 5e replaced Cat 5 in 2001. The two have the same rated bandwidth and the same construction, with 5e mitigating crosstalk further. If you still have old Cat 5 cable, Wikipedia says most of it actually meets Cat 5e specifications even though it is not certified as such, but a new purchase should say Cat 5e or better.

Which speeds each one handles

The 2.5GBASE-T and 5GBASE-T standards are the useful ones for many home users, since they let Wi-Fi access points and fast desktops go beyond gigabit without new wiring. Wikipedia’s article on them says both can run on Cat 5e or better cable, over distances up to 100 meters, and were designed so access points could reach their top speeds over existing Cat 5e cabling. So if you are moving from gigabit to 2.5 gigabit, you may not need to replace cable you already have, though you should test the link.

At 10 gigabit the picture changes. Wikipedia reports that over Cat 6, the maximum length for 10GBASE-T is reduced to 55 meters, while Cat 6a supports it over the full 100 meters. For most homes that distance is more than enough, but long runs through a large house or between buildings are where Cat 6a earns its place.

Length and the 100-meter rule

The standard run limit for twisted-pair Ethernet is 100 meters. Wikipedia explains that this is built from a permanent link of up to 90 meters plus up to 10 meters of patch cords at the ends. If you plan a long run, remember that the patch cords at each end count toward the total. Manufacturers who claim longer distances are going beyond the standard, so do not count on them.

Most home runs are far shorter than the limit, so length mostly matters for long in-wall runs. For desk and room connections, pick the length that reaches without hanging in loops, since excess cable adds clutter and nothing else. Our cable management guide covers tidying it.

Shielded or unshielded?

Standard Cat 6 cable is unshielded twisted pair, and for most homes that is what you want. Wikipedia notes that shielding may still be needed in places with high electromagnetic interference, and that when a shield is grounded at both ends it can form a ground loop that induces noise. So shielded cable is a tool for a specific problem, not an upgrade for everyone. If you think you have interference, check the equipment makers’ advice for your setup, and for in-wall or outdoor installations follow local building rules and ask a qualified installer.

Solid or stranded

Two cable constructions show up in listings. Wikipedia says the permanent link in a building is typically solid cabling run between a patch panel and a wall jack, while patch cords are stranded and allowed up to a total of 10 meters within the limit. In short: solid cable is for in-wall runs, and stranded cable is for the flexible cords at each end. For an ordinary patch cord between a PC and a wall port, a ready-made stranded cable is the right choice.

The weakest link sets the speed

A fast cable cannot lift a slow port. eero’s guide to Ethernet backhaul makes the point that a link’s speed is limited by the slowest component, including the ports at both ends, any switch in between and the cable. Check the ports on your router, switch, PC and access points before you spend on cable. A gigabit port on one end means gigabit speed, whatever the cable can do.

For home networks with a Wi-Fi mesh or access points, the same guide suggests Cat6 or higher and short runs for backhaul links. If a cable run is not possible, our guide to Wi-Fi cards for desktops covers the wireless alternative, and the category page on networking gear lists more.

If the link is slower than expected

When a connection negotiates at a lower speed than the ports allow, work from the cheapest check to the dearest. Swap the patch cord for a known-good one, try a different port on the switch or router, and confirm that both ends are rated for the speed you expect. A tester can show a miswired or damaged cable, and the equipment manuals explain how each device reports its link speed. Only after those steps is it worth replacing a run inside a wall.

The same logic helps when you add a network storage box or a second PC. Our guide to home NAS options is a good example of a device that benefits from a wired link, and a backup power plan for the router and switch is covered in our guide to choosing a UPS for a router, modem and mini PC.

A simple way to choose

• Short cords for existing gigabit or 2.5-gigabit gear: Cat 5e or Cat 6 patch cords are fine.
• New in-wall runs you want to last: Cat 6a leaves the most headroom, but ask a qualified installer and follow local rules.
• Long runs near the 100-meter limit: a quality cable rated for the full distance, and short patch cords at each end.
• Anything with heavy interference: follow the equipment makers’ advice before choosing shielded cable.

Check the listing for the category printed on the cable jacket, the length, and what the connectors are. A listing that does not state the category is not worth buying from.