How to Choose Ethernet Cable for Your Network
Ethernet cables all look more or less the same, but the category printed on the jacket makes a real difference to speed, reliability, and cost. Choose too little and a wired connection becomes a hidden bottleneck; choose too much and you pay for headroom you'll never use. The good news is that picking the right cable comes down to a few clear factors: the speed you need, the distance you're running, the electrical environment, and how the cable will be installed. This guide breaks those down and gives a straight recommendation for each situation.
What the “Cat” Numbers Mean
“Cat” is short for Category, a set of performance standards defined by the Telecommunications Industry Association for twisted-pair copper cabling. Every Ethernet cable is built from four twisted pairs of copper wire, eight wires in total, and terminates in the familiar RJ45 connector. As the category number rises, the wire twists get tighter, the shielding improves, and the cable can carry a higher frequency (measured in MHz), which translates into more data capacity. Higher isn't automatically better for you, though; it's better only if the rest of your network can use it.
The Categories Compared
Here are the categories you'll actually shop for today, with the headline specs that separate them.
|
Category |
Max speed |
Bandwidth |
Max distance |
Best for |
|---|---|---|---|---|
|
Cat5e |
1 Gbps |
100 MHz |
100 m |
Budget or existing gigabit networks |
|
Cat6 |
10 Gbps (to 55 m) |
250 MHz |
100 m at 1 Gbps |
Most homes and offices |
|
Cat6a |
10 Gbps |
500 MHz |
100 m |
Future-proofing, 10G, heavy PoE |
|
Cat8 |
25–40 Gbps |
2000 MHz |
30 m (100 m at 10G) |
Data centers, short switch links |
What about Cat7? It's best skipped. Cat7 was never recognized by the TIA standards body, it uses non-standard connectors instead of RJ45, and cable sold at retail as “Cat7” typically performs no better than Cat6a anyway. For a shielded, standards-based cable, Cat6a is the smarter buy.
The Two Numbers That Matter: Speed and Distance
Bandwidth (MHz) describes how much frequency the cable can carry cleanly, and data rate (Gbps) is the throughput your hardware can push over it. The catch is that these ratings interact with distance. Cat5e, Cat6, and Cat6a all run up to 100 meters (about 328 feet), but Cat6 only sustains its top 10 Gbps speed for about 55 meters before dropping back to 1 Gbps, while Cat6a holds 10 Gbps across the full 100 meters. Cat8's blazing 40 Gbps only reaches about 30 meters. Push a cable past its rated distance and you get signal errors and retransmissions that quietly drag down real-world speed. The practical rule: match the cable to the actual speed of your internet or switches, and to the length of the run.
Shielded vs Unshielded
Cat5e and Cat6 are usually unshielded (UTP), relying on the wire twists alone to cancel interference, which is fine for typical homes and offices. Shielded cables (STP, FTP, or S/FTP) wrap the pairs or the whole bundle in foil or braid to fight electromagnetic interference, and they matter in demanding settings: industrial spaces, runs near motors or fluorescent ballasts, or long, densely bundled cable trays. Shielding isn't free, though. Shielded cable costs more, is thicker and stiffer to pull, and must be properly grounded to work, so use it where interference is a genuine concern rather than by default.
Don't Overlook These Details
- The whole link must match: cable, connectors, keystone jacks, and patch panels all need to meet the same category. One lower-rated component drags the entire run down to its level.
- Solid vs stranded: use solid-conductor cable for permanent in-wall runs, and stranded cable for flexible patch cords that get moved and bent.
- Real copper, not CCA: choose solid bare copper over copper-clad aluminum (CCA). CCA has higher resistance, performs worse (especially with Power over Ethernet), and may not meet code.
- Jacket rating: for in-wall runs use riser-rated (CMR) cable, and for air-handling spaces above ceilings use plenum-rated (CMP) cable, as building codes require. Outdoor runs need an outdoor or direct-burial jacket.
- Power over Ethernet (PoE): if you're powering cameras, access points, or phones over the cable, Cat6 or Cat6a is preferable to Cat5e for its lower resistance and better heat handling.
Which Cable Should You Choose?
Strip away the marketing and most decisions land in one of these buckets:
- Most homes and offices: Cat6. It handles gigabit easily, supports 10 Gbps over shorter runs, is standardized, and costs little more than Cat5e.
- Future-proofing, 10G, structured wiring, or heavy PoE: Cat6a. It delivers 10 Gbps across the full 100 meters and is the sweet spot for new in-wall installations you won't want to redo.
- Tight budget or an existing gigabit-only network: Cat5e still works fine, but there's little reason to install it new when Cat6 is so close in price.
- Data centers or short, ultra-fast switch-to-switch links: Cat8, which is overkill and impractical for whole-home wiring due to its short 30-meter high-speed range.
The Bottom Line
Pick the Ethernet cable that matches your real network speed and run length rather than the highest number on the shelf. For most installations that's Cat6, stepping up to Cat6a when you're wiring in-wall for the future or running 10 Gbps and PoE, and reserving Cat8 for the data center. Use solid bare copper with the right jacket rating for in-wall work, and make sure every connector and panel in the link matches the cable.