Best Wi-Fi channel: why 1, 6 and 11, and how to pick a 5 GHz channel
Slow Wi-Fi in a block of flats in the evening is often not your broadband at all. Every network nearby shares the same handful of radio channels, and a router on a crowded or half-overlapping channel spends its time waiting and repeating itself.
Why channels overlap on 2.4 GHz
The 2.4 GHz band is narrow: channels 1 to 13 in the UK and Europe (1 to 11 in the US), with centres just 5 MHz apart, while each Wi-Fi signal is about 20 MHz wide. Channel 1 therefore spills over channels 2 to 4, and channel 3 sits on top of both 1 and 6.
Two networks on the same channel can hear each other and politely take turns. Two networks on partly overlapping channels can't decode each other, so each just sees noise, backs off and resends. That is why sharing channel 6 with a neighbour is usually better than hiding on channel 4. For what the bands themselves are good at, see 2.4 GHz vs 5 GHz, and for a picture of radio channels see What is a Wi-Fi channel? on Wirebook, our sister site.
See which channels your neighbours use
| Device | How |
|---|---|
| Windows | Command Prompt: netsh wlan show networks mode=bssid lists every network with its Channel and Signal %. netsh wlan show interfaces shows the channel you are on now. |
| Mac | Hold Option and click the Wi-Fi icon to see your current channel. For a scan of all networks choose Open Wireless Diagnostics… from that menu, then Window → Scan. |
| iPhone / iPad | Apps can't scan Wi-Fi on iOS. The free AirPort Utility app has a Wi-Fi Scanner you switch on in Settings → AirPort Utility. |
| Android | A Wi-Fi analyser app from the Play Store shows every network as a hump on a channel chart. |
| Linux | nmcli -f SSID,CHAN,SIGNAL,BARS dev wifi list |
| Router | Many routers show nearby networks or a channel graph on their wireless page: see how to log in to your router. |
Count only the strong networks (signal above about 50%, or better than about -70 dBm). Ten faint networks on channel 1 matter less than two loud ones on channel 6.
Picking a 2.4 GHz channel
- Choose the one of 1, 6 or 11 with the fewest strong networks. In Europe channel 13 is also allowed and is sometimes quiet, but some older devices from elsewhere can't see it.
- Set the channel width to 20 MHz. A 40 MHz channel on 2.4 GHz takes up two thirds of the band and clashes with nearly everyone; many routers show it as 20/40 MHz or Auto, which can still widen.
- Test at the times it used to be slow, usually evenings, from the rooms where it was worst.
5 GHz channels and DFS
| Channels | What to know |
|---|---|
| 36, 40, 44, 48 | Allowed everywhere, no radar checks, so the router starts on them straight away. Together they make one 80 MHz block. Most routers and neighbours pick these first. |
| 52 to 64 and 100 to 144 | DFS (dynamic frequency selection) channels, shared with weather and other radar. The router listens for about a minute before using one (up to 10 minutes on some channels in Europe), and must move off if it hears radar, which can make Wi-Fi drop briefly. They are often quiet because many routers avoid them. |
| 149 to 165 | Allowed in some countries, including the US and (indoors, low power) the UK. Not every device supports them. |
Widths on 5 GHz: 80 MHz is the usual balance of speed and room. 160 MHz is faster at short range but leans on DFS channels and collides more easily in flats; 40 or 20 MHz is steadier when the building is packed. Wi-Fi 6E and Wi-Fi 7 add the 6 GHz band, with lots of clean space but shorter range through walls.
When changing the channel doesn't help
- Weak signal, not interference: if the signal is poor everywhere far from the router, a different channel won't fix distance. Move the router to the middle of the home and up off the floor, or add a mesh unit: see mesh backhaul and placement.
- Non-Wi-Fi noise: microwave ovens, baby monitors, wireless cameras and some Bluetooth gadgets use 2.4 GHz too. If it drops when the microwave runs, move the device to 5 GHz.
- Auto keeps picking a bad channel: some routers choose only at start-up. Restart it at a quiet time, or set the channel by hand.
- Connected but nothing loads: that is not a channel problem; see Wi-Fi connected but no internet.
Related
Extender vs mesh vs powerline · Wi-Fi keeps disconnecting: pattern table · Mbps vs MB/s and speed tests · Mesh Wi-Fi backhaul and where to put the units · Default gateway and subnet mask explained · 2.4 GHz vs 5 GHz Wi-Fi · Double NAT and CGNAT · Log in to your router (192.168.1.1)
Questions
What is the best Wi-Fi channel for 2.4 GHz?
Channel 1, 6 or 11, whichever has the fewest strong networks near you. They are the only three that don't overlap. Avoid channels in between such as 3, 4, 8 or 9.
Is it better to share a channel or use an overlapping one?
Share. Networks on the same channel take turns politely, while partly overlapping channels just look like noise to each other and cause resends.
Should I use 20 MHz or 40 MHz on 2.4 GHz?
20 MHz. A 40 MHz channel covers two thirds of the 2.4 GHz band and clashes with neighbouring networks, so it is usually slower in practice.
What are DFS channels on 5 GHz?
Channels 52 to 144, which are shared with radar. The router must check for radar before using them and move away if it detects any, so they can cause short drops, but they are often less crowded.
Should I leave my router on Auto channel?
Usually yes. Pick by hand only if a scan shows your channel is crowded with strong networks, or Wi-Fi is slow at busy times such as evenings.
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