What this does
For 2.4GHz, ranks every channel (1-13) by how much it overlaps with networks you specify as already occupying nearby channels, and recommends the least-congested option. For 5GHz, computes exactly which 20MHz sub-channels your chosen channel and bandwidth actually occupy — since 40/80/160MHz channels bond multiple 20MHz channels together — and checks whether that range overlaps with other nearby networks. Entirely in your browser.
Why channel numbers alone don't tell the whole story
On 2.4GHz, two networks on channels that look different (1 and 3, say) can still significantly interfere with each other, since each channel's actual occupied bandwidth is wider than the 5MHz spacing between channel numbers. On 5GHz, the opposite confusion happens: a single network reported as "channel 36" at 80MHz bandwidth is actually using channels 36, 40, 44, and 48 all at once — a neighboring network on "channel 44" isn't on a different channel at all from that network's perspective, it's sharing part of the same spectrum.
FAQ
Why are 1, 6, and 11 specifically the recommended 2.4GHz channels?
Each 2.4GHz channel is spaced 5MHz apart but occupies roughly 22MHz, so adjacent channels overlap significantly. Channels need to be at least 5 apart (in channel number) to not overlap at all with standard 20MHz-wide channels — 1, 6, and 11 are the only three channels in the 1-13 range that satisfy that spacing against each other, which is why they're the standard non-overlapping trio nearly every WiFi guide recommends.
Why does this tool only support U-NII-1 and U-NII-2A (channels 36-64) for 5GHz?
Those channels don't require DFS (Dynamic Frequency Selection) to avoid interfering with radar systems, so their bonding behavior is simple and consistent. Higher 5GHz channels (U-NII-2C/Extended, 100-144) and the top of the band (149-165) have additional regulatory quirks and asymmetric grouping that vary by region — modeling them accurately would risk getting specific edge cases wrong, so this tool deliberately scopes to the range most consumer and enterprise APs actually use indoors.
What does it mean for an 80MHz network to "occupy" four channel numbers?
Channel bonding combines multiple adjacent 20MHz channels into one wider channel for more throughput — an 80MHz network anchored at channel 36 actually uses the entire 36-40-44-48 range, even though it's commonly just labeled "channel 36" in a router's settings. Any other network using channel 40, 44, or 48 — even at just 20MHz — genuinely competes for the same spectrum.
Is wider bandwidth (80MHz, 160MHz) always better?
Only when the spectrum is actually clear — wider channels mean higher potential throughput, but they also mean a much larger area of spectrum that has to be free of competing networks to actually deliver that throughput. In a dense environment (an apartment building, an office with many APs), a narrower 20 or 40MHz channel with less contention often performs more consistently than an 80MHz channel that's constantly sharing spectrum with several neighbors.
Does channel choice matter as much on 5GHz as on 2.4GHz?
Less so in most cases — 5GHz offers far more non-overlapping 20MHz channels than 2.4GHz's three, and 5GHz signals don't travel as far through walls, which naturally reduces how many networks actually compete for the same channel. It still matters in dense multi-AP environments, which is exactly the scenario this tool's overlap check is for.
Try it yourself
For the full reasoning behind channel spacing and bonding, see WiFi Channel Planning Explained. Diagnosing weak signal rather than channel congestion? WiFi Signal Strength Calculator converts RSSI into a quality percentage and an estimated distance.