Zigbee channel vs Wi-Fi interference checker

How this check works

Both radios share the same licence-free 2.4 GHz band, and the channels are fixed by their standards, so the overlap is simple arithmetic:

• Zigbee (IEEE 802.15.4) uses channels 11–26, centred on 2405 MHz through 2480 MHz in 5 MHz steps, with a 2 MHz occupied bandwidth.
• Wi-Fi (IEEE 802.11) uses channels 1–13, centred on 2412 MHz through 2472 MHz in 5 MHz steps, plus channel 14 at 2484 MHz (Japan only). Each channel is modelled at 20 MHz or the legacy 22 MHz width you select.
• A Zigbee channel is clear when its 2 MHz band misses every selected Wi-Fi band by at least 2 MHz, tight when it misses them by less than that, and overlapping when the two bands actually share frequencies.
• The recommendation ranks all 16 Zigbee channels by in-band overlap first, then by the largest gap to the nearest Wi-Fi edge, then by channel number so the order is stable and repeatable.

Every number above is a published constant, not a measurement, which is why this page can answer without a network scan or an account.

What to do with the result

1. Compare with what you run now. If your coordinator already sits on a clear channel, the honest answer is that channel choice is not your problem — leave it alone and look at placement and interference instead.
2. Change the channel in your Zigbee stack, not the router.In ZHA or Zigbee2MQTT the coordinator channel is a setting; mains-powered devices normally rejoin on their own, but a few sleepy battery devices may need to be woken or re-joined, so budget an evening for it.
3. Fix the physical layer first. On our own 46-device network, moving the coordinator onto a 1–2 m USB 2.0 extension away from the server's USB 3.0 ports and SSDs did more than any channel change. The coordinator guide covers that hardware side.
4. Remember what this page cannot see. Neighbours' networks, Bluetooth, microwave ovens and USB 3.0 noise all land in the same band and none of them appear in a channel plan.

Channel 26 caveat: channel 26 usually wins this calculation because nothing in the Wi-Fi 1/6/11 plan reaches it. Some older coordinators built on CC2530/CC2531 radios transmit at reduced power there, so if your stick uses one of those chips, channel 25 is the equivalent pick. On EFR32MG21/MG24 radios (Sonoff ZBDongle-E/P, SMLIGHT SLZB-06, Home Assistant ZBT-2) channel 26 runs at full power.

Limitations

• No live scan: the tool only knows the channels you tick. It cannot detect a neighbour's network or measure noise.
• The model treats each channel as a rectangle. Real 802.11 and 802.15.4 radios have shaped emissions and adjacent-channel rejection, so a "clear" channel can still see some energy and an "overlapping" channel can still work at short range.
• 40 MHz Wi-Fi mode in 2.4 GHz occupies two adjacent 20 MHz blocks. If you run it, tick both channels it spans.
• Zigbee channel 14 is not available: the 2.4 GHz Zigbee plan starts at channel 11.
• The recommendation is a starting point for one coordinator. Large homes with several access points and a mesh of Zigbee routers usually need a survey, not a chart.

FAQ

Which Zigbee channel is best with Wi-Fi on 1, 6 and 11?

Channels 15, 20, 25 and 26 all dodge the three non-overlapping Wi-Fi blocks. Channel 26 has the widest margin in this model; 15 and 20 sit in the narrow gaps between the Wi-Fi blocks and are the classic picks when your radio is one of the older chips that loses power on 26.

Does changing the Zigbee channel require re-pairing every device?

Usually not. The channel is a property of the network, not of each device, so most devices follow the coordinator when it moves. Sleepy battery sensors are the ones that can need a wake-up or a re-join, so plan the change for a moment when you can walk around the house.

Can Zigbee and Wi-Fi ever run on the same channel happily?

They can coexist — 802.15.4 and 802.11 use different modulation and Zigbee's low duty cycle helps a lot — but in-band overlap costs you retries and latency, and the cost grows with the number of devices. If you have a choice, take a clear channel.

Why does the tool ask for the Wi-Fi channel width?

Because the answer changes at the edges. A 22 MHz legacy channel reaches 1 MHz further on each side than a 20 MHz OFDM channel, which is exactly the margin that decides whether Zigbee 15 or 25 counts as clear.