How to Buy Ethernet Cables: what to look for

It is important to select the right Ethernet cable to ensure the best performance is obtained for the best price: Cat 5, Cat 5e, Cat 6, Cat 6a, Cat 7 what is the best buy?

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Buying Ethernet cable is not always as easy as it might seem. It is important to buy the right cable. Over-specify it and you will pay too much. Underspecify it and the performance will be impaired.

Selecting the right Ethernet cable will ensure the best performance is achieved for the best possible price.

To ensure the best cables are bought for the system, it is necessary to have a little understanding of what is needed.

Ethernet RJ45 connector on an Ethernet cable
Ethernet RJ45 connector on an Ethernet cable

Ethernet cable requirements

Many networks these days, whether home or office have the option of Wi-Fi or Ethernet cables. The advantage of using Ethernet cables is that they offer a reliable performance, and they are generally faster and have a lower latency.

However Wi-Fi is advancing and offering much higher levels of performance, but so too is Ethernet, and cable offers some distinct advantages in many circumstances.

For many connections, it is the Internet connection that is the slowest link. Even fibre broadband will be slower than the average Ethernet cables, so if it is just for Internet surfing only, then a very average Ethernet cable will suffice.

When the better Ethernet cables come into their own are when files are transferred between devices for backing up, streaming video, streaming games, and the like. The faster speeds of the more up to date better Ethernet cables can make a real difference.

Often the issues can arise when older cables are used. Most of us will have an accumulation of Ethernet cables that have been acquired over the years. These may be from earlier standards and may affect performance. If the cable has come with a new router, then it is probably one of the newer categories that will be fast.

Ethernet cable performance

There are a number of Ethernet cable categories that can be seen advertised. Cat 5, Cat 6, Cat 7 are all widely available, with Cat 5 being the oldest standard and Cat 7 the newest and with the highest performance.

Read more about . . . . Ethernet cable categories.

The different category cables have different levels of performance and as a result it is important to select a cable that will meet the requirements for the system

Using the table below it is easy to see the comparison between the levels of cable performance for when they are bought.

Ethernet Cable Performance Summary
Category Shielding Max Transmission Speed (at 100 meters) Max Bandwidth
Cat 5 Unshielded 10/100 Mbps 100 MHz
Cat 5e Unshielded 1000 Mbps / 1 Gbps 100 MHz
Cat 6 Shielded or Unshielded 1000 Mbps / 1 Gbps >250 MHz
Cat 6a Shielded 10000 Mbps / 10 Gbps 500 MHz
Cat 7 Shielded 10000 Mbps / 10 Gbps 600 MHz


One of the good things about the Ethernet cables is that they are interchangeable and they are also backwards compatible. The only real issue with using an older type cable like the Cat 5 is that it won’t support such fast data transfer speeds.

It is possible to plug a Cat 5 cable into a router that has the latest 10G Ethernet interface. The only issue is that the cable will slow the data transfer down. This may or may not be a problem dependent upon the type of file transfers.

Similarly it is possible to plug a Cat 7 cable into an old router that does not support the latest speeds.

So when buying an Ethernet cable, there is a lot of flexibility.

Ethernet cable choices

The big decision when buying Ethernet cables is making the choice of the best cable. Performance benefit over cost.

Markings on a Cat 5e Ethernet cable
Markings on a Cat 5e Ethernet cable

For domestic use Cat 5e cable is generally adequate for most applications. The Internet connection is normally the main bottle neck and if you are not continually transferring huge files, then using Cat 6 or Cat 7 cable is not likely to make much of a difference. In any case all the Ethernet equipment has to support the higher speeds anyway and any transfer will default to the lowest speed element in any connection.

If you want to be sure of getting the best speeds, then Cat 6 and Cat 6a cables are a good bet. They often don’t cost too much more than Cat 5, and for future-proofing then they are a wise option. Also Cat 5 is now obsolete so it is best not to use it.

Cat 7 cables don’t offer a huge advantage over Cat 6a in real terms at the moment. That said they do offer better shielding and this can help maintain speeds over longer distances. So for cables that are being installed, say, to wire a home, then it can often best to pay the extra to ensure the best speeds and future-proof the system for as long as possible.

For commercial systems, it is obviously worth paying the extra for the fastest cables possible. Small savings at the expense of performance can cost money over the longer term.

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