// reference · channel plan

Wi-Fi Channel Reference

2.4 GHz, 5 GHz, and 6 GHz — every channel, every DFS zone, every U-NII band. The reference I open before every site survey and gateway qualification.

— Shankar K. · US regulatory domain · Source: FCC, IEEE 802.11-2024

2.4 GHz — 2400–2483.5 MHz

14 channels, 5 MHz apart, 22 MHz wide each. Only 3 non-overlapping channels in North America: 1, 6, 11. Never use adjacent channels — the 20 dB overlap causes co-channel-like interference worse than reusing the same channel. Shared with Bluetooth, microwave ovens, Zigbee, baby monitors, and countless other 2.4 GHz ISM devices.

// channel overlap — 20 mhz

Non-overlapping (1, 6, 11)

Overlapping — avoid

Channel	Centre Freq	Range	US/Canada	Europe	Notes
1	2412 MHz	2401–2423	✓	✓	Non-overlapping #1
2	2417 MHz	2406–2428	✓	✓	Overlaps 1 and 3 — avoid
3	2422 MHz	2411–2433	✓	✓	Overlaps 1,2,4 — avoid
4	2427 MHz	2416–2438	✓	✓	Overlaps 1–5 — avoid
5	2432 MHz	2421–2443	✓	✓	Overlaps 1–7 — avoid
6	2437 MHz	2426–2448	✓	✓	Non-overlapping #2
7	2442 MHz	2431–2453	✓	✓	Overlaps 5–9 — avoid
8	2447 MHz	2436–2458	✓	✓	Overlaps 6–10 — avoid
9	2452 MHz	2441–2463	✓	✓	Overlaps 7–11 — avoid
10	2457 MHz	2446–2468	✓	✓	Overlaps 8–12 — avoid
11	2462 MHz	2451–2473	✓	✓	Non-overlapping #3 (US max)
12	2467 MHz	2456–2478	Low power	✓	Restricted in US/Canada
13	2472 MHz	2461–2483	Low power	✓	Restricted in US/Canada
14	2484 MHz	2473–2495	✗	✗	Japan only — 802.11b/DSSS only

// field note

In dense deployments I check the 2.4 GHz channel utilisation before anything else. A single legacy 802.11b client at 1 Mbps (with protection overhead) can consume 50%+ of a 2.4 GHz channel's airtime. Disabling 802.11b rates and setting channel to 1, 6, or 11 are the first two tweaks on any enterprise 2.4 GHz troubleshoot. Wireshark: radiotap.channel.freq

5 GHz — 5150–5850 MHz (US)

25 non-overlapping 20 MHz channels. Divided into U-NII bands with different DFS requirements. Channels 52–144 share spectrum with radar systems and require DFS — the AP must listen for 60 seconds (CAC) before transmitting. Higher attenuation than 2.4 GHz through walls but far more spectrum and channels available.

U-NII-1

5150–5250 MHz

No DFS

36, 40, 44, 48

Indoor preferred. No radar coexistence needed. Best for enterprise indoor deployments — clean, fast startup, no 60s CAC.

U-NII-2A

5250–5350 MHz

DFS Required

52, 56, 60, 64

Radar coexistence required. 60s CAC before transmission. Clients may not support DFS — check before deploying.

U-NII-2C

5470–5725 MHz

DFS Required

100–144 (12 ch)

Largest DFS block. Ch 120–128 share with weather radar — highest DFS event frequency. Ch 144 added in 2014, some older APs don't support it.

U-NII-3

5725–5850 MHz

No DFS (US)

149, 153, 157, 161, 165

Outdoor use allowed. No DFS in the US. Preferred for outdoor point-to-point and enterprise 5 GHz when U-NII-1 channels are occupied.

Ch	Freq (MHz)	U-NII	DFS	Valid widths	Notes
36	5180	U-NII-1	No	20/40/80/160	No DFS ✓
40	5200	U-NII-1	No	20/40/80/160	No DFS ✓
44	5220	U-NII-1	No	20/40/80/160	No DFS ✓
48	5240	U-NII-1	No	20/40/80/160	No DFS ✓
—	—	—	—	—	U-NII-2B not allocated
52	5260	U-NII-2A	Yes	20/40/80/160	60s CAC required
56	5280	U-NII-2A	Yes	20/40/80/160	60s CAC required
60	5300	U-NII-2A	Yes	20/40/80/160	60s CAC required
64	5320	U-NII-2A	Yes	20/40/80/160	60s CAC required
100	5500	U-NII-2C	Yes	20/40/80/160	Weather radar zone
104	5520	U-NII-2C	Yes	20/40/80/160	Weather radar zone
108	5540	U-NII-2C	Yes	20/40/80/160	Weather radar zone
112	5560	U-NII-2C	Yes	20/40/80/160	—
116	5580	U-NII-2C	Yes	20/40/80	—
120	5600	U-NII-2C	Yes	20/40/80	High DFS events
124	5620	U-NII-2C	Yes	20/40/80	High DFS events
128	5640	U-NII-2C	Yes	20/40/80	High DFS events
132	5660	U-NII-2C	Yes	20/40/80	—
136	5680	U-NII-2C	Yes	20/40/80	—
140	5700	U-NII-2C	Yes	20/40	—
144	5720	U-NII-2C	Yes	20	Added 2014 — limited AP support
149	5745	U-NII-3	No	20/40/80/160	No DFS ✓
153	5765	U-NII-3	No	20/40/80/160	No DFS ✓
157	5785	U-NII-3	No	20/40/80/160	No DFS ✓
161	5805	U-NII-3	No	20/40/80/160	No DFS ✓
165	5825	U-NII-3	No	20	20 MHz only — edge channel

// DFS field note

DFS events are the #1 cause of unexplained 5 GHz connectivity drops in enterprise deployments. When radar is detected, the AP moves channel within 10 seconds — clients experience a ~10 second outage. Channels 120–128 have the highest reported DFS event rate due to overlap with commercial weather radar. If DFS events are happening daily, move to U-NII-1 or U-NII-3 channels. Wireshark: wlan_mgt.fixed.action_code == 4 — DFS Channel Switch Announcement action frame

6 GHz — 5925–7125 MHz (US) Wi-Fi 6E + Wi-Fi 7

1200 MHz of clean, DFS-free spectrum allocated in the US by FCC in 2020. 59 non-overlapping 20 MHz channels. Supports 40/80/160/320 MHz channels. No legacy devices, no DFS, no radar coexistence. This is the cleanest Wi-Fi spectrum ever allocated. Countries vary — as of 2024, US, UK, EU, Brazil, Saudi Arabia, UAE, Chile, and others have allocated some or all of this band.

U-NII-5

5925–6425 MHz

Ch 1–93 (PSC)

500 MHz. First allocated by most countries. 24 non-overlapping 20 MHz channels.

U-NII-6

6425–6525 MHz

Ch 97–113

100 MHz. US only currently. 5 non-overlapping 20 MHz channels.

U-NII-7

6525–6875 MHz

Ch 117–181

350 MHz. 17 non-overlapping 20 MHz channels.

U-NII-8

6875–7125 MHz

Ch 185–233

250 MHz. Limited global adoption. 13 non-overlapping 20 MHz channels.

// preferred scanning channels (PSC) — 80 MHz primary channels

ch 5

ch 21

ch 37

ch 53

ch 69

ch 85

ch 101

ch 117

ch 133

ch 149

ch 165

ch 181

ch 197

ch 213

ch 229

PSC channels are spaced 80 MHz apart starting at channel 5. When a Wi-Fi 6E client can't find a probe response immediately, it scans PSC channels first — significantly reducing discovery time. If deploying Wi-Fi 6E, always use a PSC channel as your primary 80 MHz channel to avoid extended client scan times.

Width	Primary channel (example)	Channels available	Standard	Notes
20 MHz	Ch 1, 5, 9...	59 channels	Wi-Fi 6E / 7	Maximum density — ideal for IoT/high-client deployments
40 MHz	Ch 3 (primary 1+5)	29 channels	Wi-Fi 6E / 7	2× bandwidth vs 20 MHz
80 MHz	Ch 7 (primary 1+5+9+13)	14 channels (PSC)	Wi-Fi 6E / 7	Most common enterprise deployment width
160 MHz	Ch 15 (primary 1–29)	7 channels	Wi-Fi 6E / 7	High throughput — needs clear spectrum
320 MHz	Ch 31 (primary 1–61)	3 channels	Wi-Fi 7 only	6 GHz only, 23+ Gbps theoretical per link

// 6 GHz field note

The 6 GHz band has no DFS requirement — this is the biggest practical difference from 5 GHz. APs boot immediately without CAC delay. No radar to worry about. In Wi-Fi 7 gateway qualification, the 6 GHz radio with 320 MHz is where I see MCS 12 and 13 actually sustained in a lab environment. In the real world, 320 MHz with high MCS requires being within 3–4 metres of the AP. Wireshark: wlan_mgt.he.operation.bss_color — BSS Color in 6 GHz beacon

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— Shankar K., Wi-Fi engineer, Irving TX
 Building WiFi Analyser V2 · CWNA-109 in progress · one post every two weeks 

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