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CAT5 vs. RJ45

CAT5 vs. RJ45

RJ-45 or CAT5? This is the question.

RJ-45 and CAT5 are common terms you’ll hear when discussing wired network connections. People often use both words interchangeably to describe Ethernet cables. 

However, they are not the same thing! Neither of them should substitute for ‘Ethernet cables’ as a whole.

RJ-45 is a term that refers to a specific connector type. It can also refer to any network cable that uses the RJ-45 connector. On the other hand, CAT5 is an early category of Ethernet cables with a standard data rate of 100 Mbps.

In this article, we will explore both terms and their characteristics. Keep reading if you want to learn how they are related.

What is CAT5?

colorful twisted internet cables

Ethernet cables are categorized based on their network speed and signal qualities. The TIA and EIA defined the CAT5 specification in 1995 for computer networks.

CAT5 cables are usually unshielded and have a twisted pair design. The conductors are four pairs of color-coded twisted copper wires (eight wires in total), and cables in this category have a relatively low bandwidth capacity

CAT5 cables have a bandwidth of 100 MHz and can support up to 100 Mbps at long distances (100m). However, this category can support up to 2.5 Gbps at limited distances.

Amongst the common cabling categories (CAT5, CAT6, and CAT7), CAT5 has the lowest transmission speed and resistance to interference. Due to their lack of shielding, they are susceptible to crosstalk and interference.

In 2001, the TIA defined an ‘enhanced’ version of the CAT5 called the CAT5e. CAT5e has a data rate of 1Gbps and resists crosstalk better.

CAT5e cable with 8 wires twisted into 4 pairs

CAT5 cables are still in use because they are cheap. Also, if your network provider is on a megabit bandwidth, these cables may still fit your needs.

What is RJ-45?

RJ-45 connector in white

In 1973, Bell Labs invented the RJ-45 connector. It is an 8-pin standard interface that connects computers, TVs, and other internet-enabled devices to networks (LANs).

The name RJ-45 is the shortened form of “Registered Jack – 45.”

RJ-45 connectors are used with Ethernet cables to connect devices to wired network routers, switches, or hubs. These connectors have eight pins, so they only work with Ethernet cables that have eight wires (or less).

router hub with RJ-45 ports

The RJ-45 port is typically used by CAT5, CAT5e, CAT6, and CAT6a Ethernet cables. Paired with these cables, it typically supports internet speeds up to 1 Gbps.

There are modified versions of the RJ-45: the ARJ-45 (Augmented RJ-45) and GG45 (GigaGate 45). These connectors are not as popular as the RJ-45, but they work with CAT6 and CAT7 cables to enable faster internet speeds.

Comparison: CAT5 Vs. RJ-45

Are CAT5 cables comparable to an RJ-45? What are the similarities and differences between both?

This section discusses both terms, highlighting the differences in their functions, applications, and appearance. Enjoy. 

1/ What Are They?

a conductor with eight wires and RJ-45

By definition, CAT5 and RJ-45 are two non-competing parts of wired internet technology. They usually work together, and the presence of one does not cancel out a need for the other.

CAT5 is a category of Ethernet cables known for a standard internet data rate of 100 Mbps. Sadly, this category is phasing out as new cabling categories with higher internet speeds are coming onto the scene. 

RJ-45 is a connector type (port and jack) that allows you to connect internet-enabled devices to a wired network. These connectors are known as “data ports.” 

The RJ-45 Jack usually accompanies CAT5 and CAT6 Ethernet cables.

2/ What Are They Used For?

CAT5 Ethernet cables are largely used for internet connection in homes and small businesses. However, there are other applications for CAT5 cables outside of internet data transfer.

CAT5 cables are used in telephone communications to wire landlines; you can also use them for analog video connections. 

Paired with the right connectors, they can carry S-Video and composite video signals long distances with no quality loss. CAT5 cables also work as audio cables; you only have to fix RCA jacks to both ends of the cable to make it work.

ethernet cable with colored RJ-45 Jack

RJ-45 connectors connect computers, printers, and other devices to network routers, switches, or hubs using Ethernet cables.

3/ How Do They Look?

CAT5 cables are usually unshielded twisted pairs (UTP) and measure about 5.2 mm in diameter. 

Standard CAT5 cables consist of four twisted wire pairs. There are also CAT5 cables with two twisted wire pairs, but they aren’t considered true CAT5.

On the other hand, RJ-45 connectors have an 8-pin interface. This is why they are relevant to cable categories with 8 wires or less (CAT5, CAT5e, and CAT6).

RJ-45 connectors have an 8-pin interface

Although RJ-45 closely resembles the RJ-11 connector (used in voice/telephone technologies), it has a wider, more rectangular shape. RJ-11 jacks come with two, four, or six contacts (pins).

RJ-11 jacks come with four pins

4/ How Much Do They Cost?

RJ-45 jacks are affordable and readily available in the market compared to the modified versions. CAT5 cables are also less expensive than faster Ethernet cables in advanced categories.

Comparison Table

  CAT5 RJ-45
Description  A category of Ethernet cables  A common type of Ethernet connector 
Applications Internet data transfer

Telephone and voice communications

Video connections

Computer networking (wired internet)
Appearance Usually unshielded

Two twisted pair wires (four wires in total)

About 5.2 mm

Rectangular connector

8-pin interface

Color-coded interface

Cost Relatively inexpensive  Inexpensive 

How To Choose The Ideal Cable Category?

Unsuitable network cables can cause faults with your network connection. You must choose a cable fitting for its intended use — whether for business or home networks.

Here are a few things to consider while choosing a network cabling category.

  • Compatibility: 

a cable being plugged into the compatible Ethernet ports

Ensure that you choose a cable whose plug is compatible with the Ethernet ports on your computer, router, and other network devices. Data ports come in various types, including the RJ-45, ARJ-45, and GG45.

  • Transmission Distance: 

different ethernet cable length

Higher cabling categories are better suited for combining long-distance transmission with high network speed. 

For instance, if you’re connecting to a 2 Gbps network over a long distance, a CAT6 cable will better suit your connection than CAT5e.

  • Room for Upgrade: 

man plugging ethernet cable into router

We advise that you use a cable whose bandwidth capacity is higher than your internet provider’s network bandwidth. This will ensure you can still use the cable even if you upgrade your network. 


  • Is CAT6 CAT6a Better Than CAT5?

cat5 cat6 cat6a

Yes, CAT6 and CAT6a cables are better than CAT5 cables. They provide higher bandwidth capacity and faster internet speed to match the constantly evolving standards of transmission quality.

CAT6 and CAT6a cables improve the quality of internet, voice, and video applications. They are an upgrade from CAT5 both in terms of function and price. 

However, we consider these cabling categories a worthy investment because the price difference between them and CAT5 is quite low.

CAT6 and CAT6a cables are backward compatible, so if you’ve been using older categories, you do not have to worry about connector compatibility.


RJ-45 and CAT5 are important players in wired network connections. Most times, they work together to establish a connection. 

While CAT5 refers to a category of low-bandwidth network cables, RJ-45 refers to a type of Ethernet connector (port and plug) supported by most internet-enabled devices.  

Now that you know what both terms mean, you can make more informed decisions about your wired networks. 

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