SSID Overhead Calculator
How much of the channel beacons and probe responses take with your SSIDs, APs and basic rate, and how much fewer SSIDs, Multiple BSSID or a higher basic rate would save.
How to use this tool controls and what to look for
Describe your network (band, SSIDs, APs, basic rate) and see how much airtime beacons and probe responses take, and what would reduce it.
Controls to change
- Band: choose 2.4, 5 or 6 GHz.
- SSIDs per AP: set how many SSIDs each AP broadcasts.
- APs that hear each other on the channel: set how many APs share the channel's airtime.
- Lowest basic rate (beacons and probe responses): raise it from 1 Mbps to 6, 12 or 24 Mbps.
- Multiple BSSID (one beacon carries all SSIDs): turn it on to send one beacon for all the SSIDs.
- Probe requests per second (every AP hears each one): add scanning clients.
- 6 GHz discovery frames: on 6 GHz, add FILS Discovery frames or unsolicited probe responses.
What to look for
- Overhead grows with SSIDs × APs that hear each other. Doubling either one doubles the beacons.
- Going from 1 Mbps to 6 Mbps or higher cuts beacon airtime several times over.
- Section 3 shows how much each change would save: one SSID fewer, Multiple BSSID, or a higher basic rate.
About this tool
Every SSID sends its own beacons, about ten a second, and answers probe requests, on every AP that shares the channel. Set how many SSIDs and APs you have, the band and the lowest basic rate, and this calculator shows how much of the channel's time goes to beacons, probe responses and, in 6 GHz, FILS Discovery frames or unsolicited probe responses, before any user sends data. It then shows what each change would save, such as fewer SSIDs, Multiple BSSID or a higher basic rate, and how long one beacon takes at every basic rate.
What you'll learn
- Why SSID overhead grows with SSIDs × APs that hear each other on the same channel
- How much a 1 Mbps basic rate costs compared with 6, 12 or 24 Mbps
- What Multiple BSSID does: one beacon and one probe response carrying all the SSIDs of an AP
- How 6 GHz APs keep something on air every 20 TU with FILS Discovery frames or unsolicited probe responses
Common questions
How many SSIDs is too many?
It depends on how many APs hear each other and on the basic rate. A common rule of thumb, not a standard, is to keep management overhead under about 10% of the channel, which often means no more than 3 or 4 SSIDs per radio at a legacy basic rate.
Does raising the basic rate really help?
Yes, a lot: a 380-byte beacon takes over 3 ms at 1 Mbps but about 0.15 ms at 24 Mbps. The trade-off is that clients far from the AP can no longer decode beacons sent at the higher rate.
What is Multiple BSSID?
A way for one AP radio to advertise several SSIDs in a single beacon and a single probe response instead of one per SSID. It is widely used in 6 GHz and cuts the beacon overhead of many SSIDs to little more than one.
Free for private and educational use. This interactive model is a simplified teaching aid and may contain mistakes. It is provided as is, without warranty. Use it to understand the concepts, not as a substitute for a site survey, vendor documentation or professional design advice.