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2.4GHz vs 5GHz wifi – what’s the difference?

Many modern routers offer dual-band wifi - but which band should you use?

Thursday, 9 April, 2020

Wireless internet access might seem mysterious, but it’s actually fairly unremarkable by modern technological standards.

Your broadband router can distribute and receive digital data from wireless devices around the home, in the same way it throughputs data from devices plugged directly into it.

Information is transmitted through the ether at specific frequencies in the radio spectrum, whose electromagnetic waves range from 30 Hz to 300 GHz.

This is the same spectrum responsible for TV and – yes, you’ve guessed it – radio signals, as well as any wireless communications distributed around or to our homes.

And many of the devices in our homes and workplaces communicate across one specific frequency – 2.4GHz.

This is the frequency used by microwave ovens, Bluetooth devices, cordless phones, security alarms, baby monitors…the list goes on.

Unfortunately for consumers, 2.4GHz is also the default frequency employed by many broadband routers.

The potential for congestion is underlined every time a WiFi connection drops, out seemingly without explanation.

In reality, these dropouts could be caused by any device within the router’s range (but maybe not in your home), such as a neighbour activating their car alarm or microwaving a lasagne.

In large, densely-populated developments, you can see the potential for problems.

As a result, wireless routers meeting 2014’s 802.11ac standard tend to transmit data across both the 2.4GHz and 5GHz WiFi frequencies.

But what are the advantages of dual-band routers? And why have these two very distinct frequencies been chosen?

Getting our wirelesses crossed

WiFi was first released in 1997, in an age when desktop and laptop computers still had to be plugged into a modem to access the internet.

A standard called 802.11 was developed, using both the 2.4GHz and 5GHz WiFi frequencies – the optimal upper and lower ends of the microwave spectrum, with differing attributes.

Since 2.4GHz was compatible with more existing devices, it became the default connection frequency throughout the Noughties.

However, as our homes gradually filled with wireless connectivity, it became incrementally less effective.

Advances in WiFi standards led to the global release of 802.11n in 2009, supporting dual band routers which finally made effective use of the 5GHz frequency as well.

As well as being far less congested and prone to local conflict, 5GHz provides faster data transfers – higher frequencies are generally more efficient in this respect.

In fact, an optimal 5GHz WiFi connection could transmit data at 1,300Mbps, which compares favourably to the maximum of 600Mbps achievable over a 2.4GHz connection.

Time to change channel?

As well as being more than twice as fast, there are more than twice as many channels which 5GHz data can be transmitted across.

This higher frequency offers 23 non-overlapping channels with 20MHz of space between them.

The greater number of available channels can further reduce wireless interference, ensuring each device is broadcasting on a subtly – yet significantly – different bandwidth to the next.

By comparison, there are only 11 2.4GHz channels, with just 5MHz between one and the next. This creates a large degree of overlap on 2.4GHz channels.

You may be familiar with ISP tech support asking you to choose either channel 1, 6 or 11 on your broadband router while troubleshooting connectivity issues.

Each channel has a slightly different frequency, from 2.412 to 2.462 GHz, but only 1, 6 and 11 are completely distinct with no overlap.

And overlap between unconnected devices on a shared network tends to cause interference.

Becoming more distant

This might suggest that 5GHz connections are far superior. And in some respects, they are.

However, they can only be transmitted over a relatively short distance, whereas 2.4GHz signals are able to travel further without dropping out or degrading.

If you’re using an iPad in the same room as a dual-band router, it would ideally switch to 5GHz for optimal connection speeds.

Wander out into the garden, and the 2.4GHz frequency will be able to penetrate solid objects such as walls and windows which block higher frequencies.

Given these differing attributes, it’s perhaps unsurprising that most modern routers will be dual band, providing the benefits of both 2.4GHz and 5GHz WiFi connections at once.

Neil Cumins author picture

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Neil is our resident tech expert. He's written guides on loads of broadband head-scratchers and is determined to solve all your technology problems!

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