Channel Bandwidth 20/40 – 20 Mhz Or 40 Mhz Bandwidth? In this article, we try to understand how Wi-Fi works, what wifi ‘bands’/frequencies are, how the frequencies are shared within each band, what Wi-Fi channels are, and how to choose the best channel for your devices. Let us get right into it.
What is Wi-Fi?
Your computer and other devices connect to the internet. They do so through Wi-Fi. The best way to think about it is to imagine Wi-Fi as something between your devices and the internet. The term stands for wireless fidelity. Information from distant servers comes to your home modem through the ISP.
This information is in the form of analog signals. Because computers can’t understand analog signals, the modem has to convert them into digital signals which the computers do understand. Now, once the information has been converted into an understandable format, the challenge is to deliver the information to the right device.
Let’s say you have two devices, a laptop, and a smartphone, both connected to the internet. On the laptop you are trying to look at some cat pictures while on the smartphone a YouTube video. This data has been fetched from the internet and has been converted into digital signals. It is waiting to be delivered. This is where Wi-Fi comes into play.
A device called a Wi-Fi router will ensure that the cat pictures get routed to the correct device (in this case the laptop) and the same happens to the YouTube video (they get delivered to the smartphone).
What are Wi-Fi bands?
When we talk about Wi-Fi bands, the word bands mean bandwidth. Wi-Fi uses radio waves to send data. Radio waves have different frequencies. Wi-Fi uses two distinct frequencies. The older, legacy version uses 2.4 GHz while the newer version that is gaining popularity is the 5GHz band. Note that in other terms, 2.4 GHz is equivalent to 2400 MHz, while 5GHz translates to 5000 MHz.
What this means is that the information being sent over Wi-Fi is sent through radio waves of those two specific frequencies. Those two are not the only fixed frequencies though. In practice, 2.4 GHz is a term used to mean a range of bandwidths around 2400 MHz and the same goes for 5GHz, it is used to mean bandwidths around the 5800 MHz segment. Let us look at the upper and lower limits of these bands.
|Band||Lower limit||Upper limit|
|2.4 GHz||2400 MHz||2500 MHz|
|5GHz||5725 MHz||5875 MHz|
As you can see, devices connected to a 2.4 GHz Wi-Fi network can actually receive information not just exactly at 2.400 MHz but anywhere between 2400 MHz and 2500 MHz. The same goes for 5GHz Wi-Fi too. Devices can receive information throughout the 5725 MHz to 5875 MHz range. In fact, these frequency ranges are divided into smaller sections called channels. Let us try to understand them better.
What are Wi-Fi channels?
We now know that both 2.4 and 5GHz Wi-Fi operate within certain ranges. A term used to describe this range is the width. 2.4GHz Wi-Fi has a width of 100 MHz (2500 MHz – 2400 MHz), the same way, 5GHz Wi-Fi has a width of 150 MHz (5875 MHz – 5725 MHz).
Understanding the term width is very important. Now, the 100 MHz widths of 2.4GHz is further divided into smaller sections called channels. The following table lists them, along with their upper and lower limits.
|Channel||Upper Limit (MHz)||Lower Limit (MHz)|
Key takeaways from the table:
- 4 GHz Wi-Fi has a total of 14 channels
- Each channel has a width of 22 MHz (commonly referred to as 20 MHz channel width)
- Each channel begins after a gap of 5 MHz from the last one. Channel 1 starts at 2401 MHz and Channel 2 at 2406 MHz, for example.
- The channels overlap each other, meaning some frequencies are a part of more than one channel.2410 MHz for example, lies in both Channel 1 and Channel 2.
- When information is sent through overlapping channels, interference is caused which may slow down the internet speed.
- Channels 1, 6, and 11 have the least interference.
- Channel 6 is the default in most devices and routers default.
A pictorial representation is provided here to help understand better1:
Similar to the chart above, a chart for channels of 5GHz can also be constructed. 5GHz Wi-Fi has about 25 channels that can be used. These channels fall under different groups called UNII groups.
What Wi-Fi channel widths are possible?
In the table given above, we can see that the channel width within the 2.4 GHz can be 20 MH. Routers can also use a special technique called ‘channel bonding’, this lets them join together two or more channels to create a wider stream for information exchange.
This process is often called widening the pipe width. Bonding allows routers to merge channel widths in powers of 20 MHz, which can be used to answer our question – the possible widths are 20 MHz, 40 MHz, 80 GHz, and even 160 GHz.
Here’s a pictorial representation showing the different channels possible on 2.4 GHz Wi-Fi2:
Is 20 MHz or 40 MHz channel width better for 2.4 GHz Wi-Fi?
To answer this question, we take note of a few things from the diagram shown in the previous section:
- Having a 40 MHz channel width only leaves one working channel possible. The other channels are either not allowed by the government authorities or are simply under too much interference due to overlapping that it would actually be downgrading the speeds using those.
- With a 20 MHz channel width, channels 1, 6 11, and 14 are available. These channels have very low overlap and are very clear usually. But note that channel 14 partially lies beyond the 2.4 GHz upper limit. It can therefore not be used. That leaves us with channels 1, 6, and 11 as the best channels.
Because more channels are better than fewer channels, the 20 MHz channel width is recommended for a 2.4 GHz Wi-Fi setup. Having a 40 MHz channel width would cause all devices to talk in the same channel and thus cause too much noise.
Is 20 MHz or 40 MHz channel width better for 5 GHz Wi-Fi?
The different channels available with 5 GHz Wi-Fi under both, 20 MHz and 40 MHz channel widths are summarised as follows:
|20 MHz as the channel width||40 MHz as the channel width|
|Channel 36||Channels 36 through 40|
|Channel 40||Channels 44 through 48|
|Channel 44||Channels 149 through 153|
|Channel 48||Channels 157 through 161|
We can see that the 20 MHz channel width provides more channels for the devices to work with.
While generally, more channels mean better connectivity, we must not forget that the 40 MHz channel width provides wider channels too. These channels are twice the width of 20 MHz and can carry significantly more throughput when used at top capacity. It is recommended to use 40 MHz channel width on 5 GHz Wi-Fi for the following reasons:
- The channels are relatively wider than 20 MHz
- The channels have an almost negligible amount of interference and overlap
- The channels combined can provide a much faster data transfer rate as compared to the channels of 20 MHz channel width.
- Some routers are programmed to prefer 20 MHz channel width on 2.4 GHz and 40 MHz channel width on 5 GHz band, so for best results 40 MHz channel width is recommended for 5 GHz band Wi-Fi.
What about 80 MHz channel width in the 5 GHz band?
The wonders of Wi-Fi bonding allow 5 GHz networks to push channel limits a step further and even get 80 MHz wide channels. When using it, the following channels are available without interference for use by client devices (laptops, phones, etc.):
- Channels 36 through 48
- Channels 149 through 161
An 80 MHz channel width would be recommended if the Wi-Fi space is sparse and there are very few connecting devices and other routers within range. The reason being that 80 MHz is quite a wide range and as the range widens, its chances of interfering with other channels increases.
80 MHz channel width is therefore only recommended when very few Wi-Fi routers are present within range. For most other purposes, 40 MHz is still the optimum channel width for 5GHz.
Channel Bandwidth 20/40
WiFi channel widths: 20MHz vs 40MHz
The two-channel widths have their distinct sets of advantages and disadvantages. While the 20MHz provides more channels to work with, 40MHz provides wider channels. The 20MHz channel width provides the higher penetrating ability, 40MHz allows for the least interference possible.
When deciding 20MHz vs 40MHz, make sure to keep your own WiFi environment in mind. If you have a lot of devices connected all the time, consider changing to the 5GHz band and switching channels to a width of 40MHz. If you live/work in a relatively sparse area, stick to 20MHz and use the 2.4 GHz band.
Changing the channel widths on your router
The difference between different router models and routers of different manufacturers can be very stark. As such, the steps listed here should be used as a general guideline. The actual options might differ on your own router and the process could be entirely different.
It is recommended that you check the manufacturer’s website or the owner’s manual for instructions pertaining to your specific model. The process described below works for TP-Link and some models of D-Link.
Here are the steps to change channel width on your Wi-Fi router:
- Firstly we have to access the router settings page. Most routers use the default gateway for this. The default gateway IP is 192.168.0.1.
- Open a web browser (For example Google Chrome) and enter the gateway IP mentioned in the previous step.
- This should load the router settings, enter the username and password if it is asked. If you do not know the password and/or the username, refer to the packaging of the router or the owner’s manual. Many routers also have a default username of “admin” and password as “12345678”.
- Once logged in into the router, click ‘Wireless’ and head over to the ‘Basic Settings’ option under it.
- Channel and channel width dropdown options should be visible.
- Click on the channel width dropdown and choose the desired channel width.
- Click the save button.
- Safely shut down the router and switch it back again.
- The router might take a few extra minutes to set up the new changes.
- You will have successfully changed the router channel width on your network.
A note about the ‘Auto’ option. The dropdown list might also offer you an auto option for the channel width. The routers use protocols to try and choose the best channel and channel width for you according to the Wi-Fi traffic that it detects in your area. Most enthusiasts do not set it to Auto and instead choose a custom value. We have successfully changed the router settings.
In today’s world Wi-Fi is a technology that we simply can’t live without. The ability of the devices to communicate with each other at staggering speeds has helped the internet of things become what it is today. As a paid service, each consumer deserves the optimum speed they can get with their setup.
Understanding Wi-Fi bands can help you choose a better network setup for your home or office. The importance of Wi-Fi channels can also not be stressed enough. After all, the channels are what the devices actually communicate in.
Meet Eriksson Ray. I’m the co-founder of TenWitch.com. Our website is dedicated to the coverage of product reviews, buyer’s guides, best lists, etc. We can help you to choose a new modem/router or troubleshooting your Internet connection.