Wi-Fi devices automatically set and adjust their channel numbers as part of the communication protocol. Operating system and utility software on computers and routers keep track of Wi-Fi channel settings being used at any given time. Under normal conditions, users don't need to worry about these settings. However, users and administrators may wish to change their Wi-Fi channel numbers in certain situations.
2.4 GHz Wi-Fi Channel NumbersWi-Fi equipment in the U.S. and North America features 11 channels on the 2.4 GHz band. Channel 1 operates at a center frequency of 2.412 GHz, channel 11 operates at 2.462 GHz, with other channels operating at frequencies in between, evenly spaced at 5 MHz (0.005 GHz) intervals. Wi-Fi gear in Europe and other parts of the world also supports channels 12 and 13 running at the next higher frequency levels 2.467 and 2.472, respectively. A few additional restrictions and allowances apply in certain countries: for example, 2.4 GHz Wi-Fi technically supports 14 channels, although channel 14 is only available for old 802.11b equipment in Japan.
Because each 2.4 GHz Wi-Fi channel requires a signaling band roughly 22 MHz wide, radio frequencies of neighboring channels numbers significantly overlap each other.
5 GHz Wi-Fi Channel Numbers5 GHz offers significantly more channels than does 2.4 GHz Wi-Fi. To avoid issues with overlapping frequencies, 5 GHz equipment restricts available channels to certain numbers within a larger range. For example, popular 5 GHz channels in many countries include 36, 40, 44, and 48 while other numbers in between are not supported. Channel 36 operates at 5.180 GHz with each channel offset by 5 MHz, so that Channel 40 operates at 5.200 GHz (20 MHz offset), and so on. The highest frequency channel (165) operates on 5.825 GHz. Equipment in Japan supports an entirely different set of Wi-Fi channels that run at lower frequencies (4.915 to 5.055 GHz) than the rest of the world.
Reasons to Change Wi-Fi Channel NumbersMany home networks in the U.S. utilize routers that by default run on Wi-Fi channel 6 on the 2.4 GHz band. Neighboring wireless home networks that run over the same channel generate radio interference that can cause significant network performance slowdowns for users. Re-configuring a network to run over a different channel helps minimize these slowdowns.
How To Change Wi-Fi Channel NumbersTo change channels on a home wireless router, log into the router's configuration screens and look for a setting called "Channel" or "Wireless Channel." Most router screens provide a drop-down list of supported channel numbers to choose from.
Most other devices on a local network will auto-detect and adjust their channel numbers to match that of the router or other wireless access point with no action needed. However, if certain devices fail to connect after changing the router's channel, visit the software configuration utility for each of those devices and make matching channel number changes there. The same configuration screens can also be checked at any future time to verify the numbers in use.
Choosing The Best Wi-Fi Channel NumberIn many environments, Wi-Fi connections perform equally well on any channel: Sometimes the best choice is to leave the network set to defaults and not try to make any changes. Performance and reliability of connections can vary greatly across channels, however, depending on the sources of radio interference and their signal frequencies. No single channel number is inherently "best" relative to the others. For example, some users prefer to set their 2.4 GHz networks to use the lowest possible (1) or highest possible (11, or 13, depending on country) channels to avoid midrange frequencies because some home Wi-Fi routers default to the middle channel 6. However, if neighboring networks in turn do the same thing, severe connectivity issues can result.
In extreme cases, users may need to coordinate with their neighbors on the channels each will use, to keep separation between them.
Some more technically-inclined users run network analyzer software to test a local area for existing wireless signals and derive a safe channel to use based on the results. The "Wifi Analyzer" (farproc.com) app for Android is a good example of such an application, which plots the results of signal sweeps on graphs and recommends appropriate channel settings at the push of a button. Different Wi-Fi analyzers also exist for other types of platforms. The "inSSIDer" (metageek.net) utility also supports related functionality and is also available on non-Android platforms.
Less technical users, on the other hand, may simply try and test each channel individually and pick one that seems good; typically more than one will work equally well.
Because the effects of signal interference vary over time, what appears to be the best channel one day may turn out later to not be good. Administrators should periodically monitor their environment to see if conditions have changed such that a Wi-Fi channel change is needed.