Channel width specifies how much bandwidth your radio is using within the available spectrum. Using more bandwidth can speed up your wireless network, but it can also cause more interference for adjacent access points. There are several things to consider before increasing the channel width.
On 2.4Ghz, access points typically use 20Mhz wide channels. On 5Ghz, the access points will typically use 40Mhz wide channels for 802.11n models, and 80Mhz wide channels on 802.11ac models.
Channels that are 20Mhz wide are typically known as “narrow channels”, while those that are wider than 20Mhz are known as “wide channels”. The 802.11n specification uses High Throughput(HT) and Very High Throughput(VHT) designations.
Narrow channel = 20Mhz / HT20
Wide Channel = 40Mhz / HT40
802.11ac Wide Channel = 80Mhz / VHT80
Consider the questions below, before enabling wide channels on your network.