What is UNII-5?
UNII-5 is the lowest of the four sub-bands that make up the 6 GHz Wi-Fi band. It covers 5.925 to 6.425 GHz, a 500 MHz block with 20 MHz channels 1 to 93, which makes it the largest 6 GHz sub-band. UNII stands for Unlicensed National Information Infrastructure, the FCC's name for these bands. Wi-Fi 6E (802.11ax in 6 GHz) and Wi-Fi 7 (802.11be) devices use it; older Wi-Fi devices can't see 6 GHz networks at all.
The four 6 GHz sub-bands
| Sub-band | Frequency range | 20 MHz channels | US access point rules (FCC) |
|---|---|---|---|
| UNII-5 | 5.925 to 6.425 GHz | 1 to 93 | Low-power indoor, or standard power with AFC |
| UNII-6 | 6.425 to 6.525 GHz | 97 to 113 | Low-power indoor; no standard power |
| UNII-7 | 6.525 to 6.875 GHz | 117 to 181 | Low-power indoor, or standard power with AFC |
| UNII-8 | 6.875 to 7.125 GHz | 185 to 233 | Low-power indoor; no standard power |
Together the four sub-bands span 1,200 MHz, with 59 channels at 20 MHz. 6 GHz channel numbers start over at 1 and go up by 4. A channel's center frequency is 5.950 GHz plus 5 MHz times the channel number, so channel 1 is centered at 5.955 GHz. Don't confuse 6 GHz channel 1 with 2.4 GHz channel 1.
US rules for UNII-5
In the United States (FCC), UNII-5 allows both main classes of access point:
- Low-power indoor (LPI): indoor-only access points at limited power, with no database check.
- Standard power: higher power, indoors or outdoors, but only on the channels and power levels an AFC (Automated Frequency Coordination) system approves for the access point's location. AFC protects the licensed fixed microwave links that also use this spectrum.
UNII-5 has no DFS requirement. DFS is a 5 GHz rule.
Using UNII-5 in practice
Its size makes UNII-5 the easiest place to fit wide channels: it holds six full 80 MHz channels and three full 160 MHz channels. The Wi-Fi Alliance's preferred scanning channels (PSCs), which clients scan to find 6 GHz networks quickly, fall on channels 5, 21, 37, 53, 69 and 85 in this sub-band. Many regulators outside the US, including the European Union, opened only the lower part of the 6 GHz band, roughly matching UNII-5, so it's the part of 6 GHz most likely to be available abroad. The Wi-Fi Alliance also requires WPA3 (or Enhanced Open for open networks) on 6 GHz, so WPA2-only settings don't carry over.
For the CompTIA A+ exam
Core 1 (220-1201) objective 2.2 lists 6 GHz among the Wi-Fi frequencies and covers channel regulations and channel selection. The UNII-5 name isn't in the objectives, so focus on the big picture: 6 GHz is used by Wi-Fi 6E and Wi-Fi 7, offers many non-overlapping channels, and has shorter range than 2.4 or 5 GHz.