Kernaali ToolsBand is not a speed rating
PHY rate depends on generation, channel width, spatial streams (NSS), modulation and coding (MCS), guard interval (GI), and the capabilities negotiated by both ends. Regulatory limits and channel availability constrain the choices. Application throughput is lower and also loses airtime to contention, retries and protocol overhead.
| Generation | Usual bands | Channel widths in the standard |
|---|---|---|
| Wi-Fi 4 · 802.11n | 2.4 / 5 GHz | 20, 40 MHz |
| Wi-Fi 5 · 802.11ac | 5 GHz | 20, 40, 80, 160 MHz (also 80+80) |
| Wi-Fi 6 · 802.11ax | 2.4 / 5 GHz | 20, 40; 80 / 160 MHz on 5 GHz |
| Wi-Fi 6E · 802.11ax | Adds 6 GHz | 20, 40, 80, 160 MHz; same ax PHY |
| Wi-Fi 7 · 802.11be | 2.4 / 5 / 6 GHz | 20, 40; 80 / 160 on 5 / 6; 320 on 6 GHz |
A controlled rate comparison
Full-channel, single-user 802.11ax; MCS 11, 1024-QAM, coding 5/6, GI 0.8 μs. Values below are theoretical PHY Mbps, rounded to one decimal. They are not measured goodput or Internet speed.
| Width | 1 spatial stream | 2 spatial streams |
|---|---|---|
| 20 MHz | 143.4 | 286.8 |
| 40 MHz | 286.8 | 573.5 |
| 80 MHz | 600.5 | 1,201.0 |
| 160 MHz | 1,201.0 | 2,402.0 |
A 2-stream client cannot use four streams just because the AP has four antennas. OFDMA resource-unit allocation, a lower MCS or a longer GI changes these rates.
Choose width for the site
2.4 GHz: begin with 20 MHz where spectrum is shared. Forty MHz uses a large part of the band.
5 GHz: 20/40 MHz favors channel reuse; 80 MHz can help fast nearby clients when airtime is available. Wider is not always faster.
6 GHz: wider channels become practical where spectrum, power rules and client support allow. 320 MHz requires compatible Wi-Fi 7 equipment.
Before changing radio settings
Record channel utilization, retries, signal and current PHY rates. Compare a wired local speed test with a Wi-Fi local test before blaming the ISP.
DFS may delay startup or move a 5 GHz channel after radar detection. Set the real country and comply with indoor/outdoor and power restrictions.
MLO can use multiple links on supported Wi-Fi 7 devices. Do not add advertised radio maxima and call that one client’s expected throughput.