Spectrum Foundation
The Wi-Fi spectrum, explained end to end
One page covering every band Wi-Fi uses — 2.4, 5, 6 and 60 GHz — what each is good for, how much usable spectrum you really get, and where the regulatory landmines are.
Interactive
The spectrum, end to end
Five pieces of radio spectrum, four of them Wi-Fi, each with its own physics and its own regulatory baggage. Click a band to see what it actually gives you — and what it takes away.
2.4 GHz3.556760 GHz
Widths on this chart are indicative, not to scale — 60 GHz alone is wider than everything to its left combined.
2.4 GHz
The band you cannot switch offFrequency range
2.400 – 2.4835 GHz
Total width
~83.5 MHz
Usable channels
3 non-overlapping 20 MHz channels
Channel widths
20 MHz only
Standards
802.11b/g/n/ax
Relative reach
Longest
Channel plan
1611
Channels 1, 6 and 11. That is the entire usable plan — 3, 9 and everything between create adjacent-channel interference for two neighbours at once.
What it is good for
- Reaches furthest and penetrates walls better than any other Wi-Fi band
- Universal device support, including the cheapest IoT modules
- The only band many sensors, thermostats and badge readers can use
- Useful as coverage of last resort at warehouse edges and outdoor fringes
Where it hurts
- Shared with microwave ovens, Bluetooth, Zigbee, video senders and cordless phones
- Only three clean channels, so density collapses almost immediately
- Legacy 802.11b rates drag the whole cell down if you leave them enabled
- Non-Wi-Fi interference here is invisible to Wi-Fi tools — you need a spectrum analyser
Design rule
Treat it as an IoT band. Disable the 2.4 GHz radio on 50–70% of your access points in a dense deployment, use 20 MHz only, and stop trying to make it perform.
CBRS
Not Wi-Fi, but on the same shortlistFrequency range
3.550 – 3.700 GHz (US)
Total width
150 MHz
Usable channels
Three-tier shared access
Channel widths
10 / 20 MHz carriers
Standards
LTE / 5G NR private networks
Relative reach
Long (outdoor)
Access is policed by a Spectrum Access System with three tiers: incumbents first, Priority Access Licences second, General Authorized Access third. You do not pick a channel — the SAS assigns one.
What it is good for
- Deterministic handover across large outdoor areas where Wi-Fi roaming struggles
- SIM-based identity, which is harder to spoof than a pre-shared key
- Excellent for ports, mines, campuses and anywhere access point density would be absurd
- Licence-free at the GAA tier in the US
Where it hurts
- Client device support is a fraction of Wi-Fi, and each device needs a SIM
- Cost per square metre is far higher than Wi-Fi for indoor coverage
- US-specific — other regions have their own, incompatible shared-spectrum schemes
- Requires SAS integration and professional installation certification
Design rule
Consider it when you need wide-area outdoor coverage with cellular-grade handover. For an office building, Wi-Fi wins on cost and device support almost every time.
5 GHz
Where the real work happensFrequency range
5.150 – 5.850 GHz (UNII-1 to UNII-3)
Total width
~500 MHz
Usable channels
Up to 25 channels with DFS, ~9 without
Channel widths
20 / 40 / 80 / 160 MHz
Standards
802.11a/n/ac/ax/be
Relative reach
Medium
Channel plan
3640444852566064100104108112116120124128132136140144149153157161165
Amber channels are DFS — shared with radar. An access point must listen before transmitting and vacate within 10 seconds of a detection. Channels 120–128 are weather radar and cause the most disruptive false positives.
What it is good for
- Enough spectrum for a real channel plan, especially with DFS enabled
- Universal support on every laptop and phone made this decade
- Good balance of range and capacity — still the workhorse coverage band
- Preamble puncturing in Wi-Fi 7 recovers channels partially blocked by neighbours
Where it hurts
- DFS radar events drop every client on the access point without warning
- Without DFS you are down to about nine channels, which forces co-channel reuse
- Congested in dense urban buildings where every neighbour is also here
- 80 and 160 MHz channels raise the noise floor 6 and 9 dB, shrinking coverage
Design rule
Decide the DFS question deliberately and write down why. Near an airport or coastal radar, stay off it. Everywhere else, enabling DFS is the single biggest free capacity gain available.
6 GHz
The first genuinely clean bandFrequency range
5.925 – 7.125 GHz (US) · 5.925 – 6.425 GHz (EU/UK)
Total width
Up to 1200 MHz
Usable channels
59 channels (US) · 24 channels (EU/UK)
Channel widths
20 / 40 / 80 / 160 / 320 MHz
Standards
802.11ax (Wi-Fi 6E) and 802.11be (Wi-Fi 7) only
Relative reach
Shortest
Channel plan
5*21*37*53*69*85*101*117*133*149*165*181*197*213*229*
Starred channels are Preferred Scanning Channels — every 16th channel. Clients scan these first, so putting your 6 GHz BSS on a PSC dramatically improves how quickly devices find it.
What it is good for
- No legacy clients permitted, so no protection overhead and no 20-year-old device dragging the cell down
- Two to five times the spectrum of 5 GHz, depending on your regulator
- WPA3 and Protected Management Frames are mandatory — security is not optional here
- Wide channels are actually viable because there is room for a plan
Where it hurts
- Roughly 20–30% less coverage area per access point than 5 GHz
- Indoor Low Power operation caps your transmit power, and outdoors needs AFC coordination
- Clients cannot find the network without Reduced Neighbor Reports, FILS or broadcast probe responses
- Client support is still well under half of a typical enterprise estate
Design rule
Survey at 6 GHz — do not extrapolate from 5 GHz. Budget 15–25% more access points than the 5 GHz design it replaces, and default to 80 MHz channels on PSC.
60 GHz
The specialistFrequency range
57 – 71 GHz
Total width
Up to 14 GHz
Usable channels
Channels 2.16 GHz wide
Channel widths
2.16 GHz and multiples
Standards
802.11ad / 802.11ay (WiGig)
Relative reach
Room-scale
Channel widths here are measured in gigahertz, not megahertz — a single 60 GHz channel is wider than the entire 5 GHz band.
What it is good for
- Enormous throughput for fixed point-to-point links and wireless backhaul
- Effectively no congestion, because almost nobody is using it
- Excellent for wireless docking, AR/VR tethering and short-range video
- Ubiquiti and others sell affordable building-to-building bridges on it
Where it hurts
- Oxygen absorption is severe — range is measured in tens of metres indoors
- A human body is an effective wall; the link drops when someone walks through it
- Requires line of sight, and rain fade matters on outdoor links
- Not a general-purpose access technology, whatever a vendor tells you
Design rule
Use it for what it is good at: fixed links between two points you control, with clear line of sight. Do not plan client coverage on it.
Go deeper
The written references behind the chart above.
RF Fundamentals Foundation
RF fundamentals: dBm, SNR, MCS and why signal strength lies
The small amount of RF maths that explains most Wi-Fi behaviour: the decibel, noise floor, SNR, and the modulation ladder that turns signal quality into throughput.
Spectrum Intermediate
DFS channels: when to use them and when to stay away
DFS roughly triples your 5 GHz channel budget and occasionally drops every client on an AP. A decision framework, plus how to test your site before committing.
Spectrum Advanced
6 GHz in practice: LPI, Standard Power and AFC
How the 6 GHz power classes actually constrain a design, what AFC does, why your 6 GHz SSID is invisible, and the coverage penalty nobody puts on the data sheet.
Signal, not noise.
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