WiFi PHY Rates (MCS)
Pick standard, channel width, guard interval and spatial streams to get the PHY rate per MCS. PHY rate is the link ceiling, not real throughput.
PHY rate per MCS
| MCS | Modulation | Code | Mbps |
|---|
The highlighted row is the highest PHY rate for this combination.
How it is computed · 802.11 PHY formula
Formula PHY = (Nsd · Nbpscs · R · Nss) / Tsym
Nsd data subcarriers, by channel width. For
HT/VHT (3.2 µs symbol): 20→52, 40→108, 80→234, 160→468.
For HE/EHT (12.8 µs symbol): 20→234, 40→468, 80→980,
160→1960.
Nbpscs bits per subcarrier:
BPSK 1, QPSK 2, 16-QAM 4,
64-QAM 6, 256-QAM 8, 1024-QAM 10 (HE+),
4096-QAM 12 (EHT).
R code rate of the MCS (e.g. 5/6 for MCS9). Nss spatial streams (1–8).
Tsym symbol + GI. For HT/VHT:
3.2 + 0.8 = 4.0 µs (long) or 3.2 + 0.4 = 3.6 µs
(short). For HE/EHT: 12.8 + {0.8, 1.6, 3.2} =
13.6 / 14.4 / 16.0 µs.
The PHY rate is the link ceiling (physical-layer data rate), not usable throughput: MAC overhead, contention, preambles and retransmissions bring it down in practice.
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How it works
The tool generates the WiFi physical-layer (PHY) rate table for the standard you choose: 802.11n (HT, MCS 0–7), 802.11ac (VHT, 0–9), 802.11ax (HE, 0–11) or 802.11be (EHT, 0–13), combined with the channel width (20–160 MHz), the guard interval and the number of spatial streams (1–8). It lists the rate of every MCS, highlights the maximum and details the internal parameters: data subcarriers (Nsd) and OFDM symbol duration (Tsym).
The math uses the IEEE 802.11 physical-layer formula: PHY = (Nsd × Nbpscs × R × Nss) / Tsym, where Nsd is the data-subcarrier count for the chosen width (HT/VHT: 20→52, 40→108, 80→234, 160→468; HE/EHT with OFDMA: 20→234, 40→468, 80→980, 160→1960), Nbpscs the bits per subcarrier of the modulation (BPSK 1 up to 4096-QAM 12), R the coding rate of the MCS and Tsym the symbol plus guard interval (3.2 µs + 0.4/0.8 µs in HT/VHT; 12.8 µs + 0.8/1.6/3.2 µs in HE/EHT). The PHY rate is the ceiling of the link, not the useful throughput.
Example: where do the 866.7 Mbps of WiFi 5 come from?
- Typical setup: 802.11ac (VHT), 80 MHz channel, MCS9 (256-QAM, R = 5/6), 2 streams and short GI (Tsym = 3.2 + 0.4 = 3.6 µs).
- At 80 MHz there are
Nsd = 234subcarriers and 256-QAM contributesNbpscs = 8bits per subcarrier. PHY = (234 × 8 × 5/6 × 2) / 3.6 = 866.7 Mbps. With long GI (4.0 µs) the same combination drops to 780 Mbps.