Answer: It depends on your wireless environment and device capabilities.
Unlike the 2.4 GHz band 5 GHz has no overlapping channels if a 20 MHz wide channel plan is used. The design issue that needs to be managed is if clients support the configured channels and if the the channels congested due to neighboring devices.
One of the first things you should research while determining the channel(s) you should set your access point(s) to, is which channels your devices support. Some devices will not support certain channels, so if you have an access point set to those channels, you will not be able to connect to the network. An easy way to find this information is going to https://clients.mikealbano.com/. This website is a large list of devices and their capabilities. Scroll through to find your devices and the channels they support.
Spectrum Graph (Wireless Environment)
This graph will show you all of the access points within range of your device and the channels they are using. The importance of the spectrum graph is that you can see which channels are congested, which channels are barely used, and which channels are completely open.
As you can see from this spectrum graph, a lot of channels are being used by many different networks. This is an example of a high density environment like an office building or apartment complex.
This spectrum graph is an example of a single one or two story building environment where there is only one network over many channels. As you can see, there is much more room for wider channels as there is less congestion. Before this network was set up, every channel was open for use.
Choosing a Channel
After determining which channels your devices are capable of using, and looking at your spectrum graph, you have a much better idea of which channel to choose.
If there is an open channel that your devices support. Then, that is probably the best channel to assign to your access point.
If there are no open channels, find a channel that has the least congestion and the worst signal to your device. The stronger the signal from other access points, the more likely you will experience interference.
Choosing a Channel Width
Technically, one channel in the 5 GHz band is 20 MHz wide. These channels can be bonded together to create wider channels, which in turn, allows for more throughput of data. Channel widths can be 20 MHz, 40 MHz, 80 MHz, and 160 MHz.
An example of different channel widths on the spectrum graph.
Choosing the right channel width depends on the wireless environment and desired throughput. The wider the channel is, the more potential throughput an access point can transmit to a client device. But, in congested environments, using wider channels will allow a lot more potential for wireless interference. If most or all channels are not utilized by other networks, 40 or 80 MHz channel widths are perfectly acceptable to use. If the environment is congested and access points are on most or every channel, a 20 or 40 MHz channel is much more suitable as it will give a more stable and reliable connection.
Download a free trial of our WiFi Scanner app to help with configuring the best 5 GHz channel.