Channel Width Calculator
Trade Wi-Fi channel width against PHY rate, noise-floor penalty and how many non-overlapping channels remain for reuse.
Inputs
PHY Data Rate
1,196Mbps
Expected TCP Throughput
778Mbps
Noise-Floor Penalty vs 20 MHz
6.0dB
Non-Overlapping Channels Available
6
Data Subcarriers
980
Step by step
Values used
Channel width = 80 MHz; Spatial streams = 2 streams; Bits per subcarrier (modulation) = 1024-QAM (10); Coding rate = 83 %; MAC efficiency after overhead = 65 %
Channel Width
PHY rate = data subcarriers × bits per subcarrier × coding rate × spatial streams ÷ 13.6 µs symbol time; noise penalty = 10·log10(width ÷ 20).
PHY Data Rate
= 1,196 Mbps
Expected TCP Throughput
= 778 Mbps
Noise-Floor Penalty vs 20 MHz
= 6.0 dB
Non-Overlapping Channels Available
= 6
Data Subcarriers
= 980
How it works
Doubling the channel width doubles the subcarrier count and therefore the PHY rate, but it also doubles the received noise power, which costs 3 dB of link budget per doubling and halves the number of channels available for reuse. Wide channels are the single most over-used Wi-Fi setting: 80 MHz on a dense floor buys headline speed on one AP and co-channel interference on every other one.
Formula
Channel Width
PHY rate = data subcarriers × bits per subcarrier × coding rate × spatial streams ÷ 13.6 µs symbol time; noise penalty = 10·log10(width ÷ 20).
- subcarriers
- 802.11ax data subcarriers for the chosen width
- 13.6 µs
- 12.8 µs OFDM symbol plus a 0.8 µs guard interval
Frequently Asked Questions
How is Channel Width calculated?
PHY rate = data subcarriers × bits per subcarrier × coding rate × spatial streams ÷ 13.6 µs symbol time; noise penalty = 10·log10(width ÷ 20). Doubling the channel width doubles the subcarrier count and therefore the PHY rate, but it also doubles the received noise power, which costs 3 dB of link budget per doubling and halves the number of channels available for reuse.
Why does Channel Width matter?
Wide channels are the single most over-used Wi-Fi setting: 80 MHz on a dense floor buys headline speed on one AP and co-channel interference on every other one.
What values do I need to enter?
This calculator takes 5 inputs: Channel width, Spatial streams, Bits per subcarrier (modulation), Coding rate, MAC efficiency after overhead. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.