How to Calculate Wi-Fi Data Rate?

The Wi-Fi OTA data rate formula:

(OTA: Over-The-Air)

Data Rate=N_SS​×N_SD​×log_2​(M)×R÷T_SYM

Symbol	Meaning
$N_{SS}$​	Number of spatial streams
$N_{SD}$​	Number of data subcarriers
${\log }_2(M)$	Bits per subcarrier per symbol (determined by modulation)
$R$	Coding rate
$T_{SYM}$​	Symbol duration (symbol time + guard interval)

The symbol duration is:

$$T_{SYM}=T_{FFT}+T_{GI}$$​

Where $T_{FFT}$​ is the OFDM symbol (FFT) duration and $T_{GI}$ is the short guard interval.

Number of data subcarriers N_SD​

Channel Width	Wi-Fi 4 (802.11n)	Wi-Fi 5 (802.11ac)	Wi-Fi 6 (802.11ax)
20 MHz	52	52	234
40 MHz	108	108	468
80 MHz	—	234	980
160 MHz	—	2×234 = 468	2×980 = 1960

Bits per symbol log⁡₂(M)

Modulation	log⁡2(M)
64-QAM (Wi-Fi 4 max)	6
256-QAM (Wi-Fi 5 max)	8
1024-QAM (Wi-Fi 6 max)	10

Coding rate R

All three standards share the same maximum coding rate:

$$R=\frac{5}{6}$$

Symbol duration T_SYM

Standard	TFFT	TGI(Long)	TGI(Short)	TSYM(Short GI)
Wi-Fi 4 (802.11n)	3.2 μs	0.8 μs	0.4 μs	3.6 μs
Wi-Fi 5 (802.11ac)	3.2 μs	0.8 μs	0.4 μs	3.6 μs
Wi-Fi 6 (802.11ax)	12.8 μs	0.8 μs	3.2 μs	13.6 μs

Worked Examples

Wi-Fi 4 (802.11n): 40 MHz, 4×4 MIMO, 64-QAM, 5/6, Short GI

$$\text{Data Rate}=4\times 108\times 6\times \frac{5}{6}÷3.6\mu s$$$$=\frac{4\times 108\times 6\times 5}{6\times 3.6\times 10^{-6}}=\frac{12960}{21.6\times 10^{-6}}\approx 600\text{Mbps}$$

Wi-Fi 5 (802.11ac): 80 MHz, 1×1, 256-QAM, 5/6, Short GI

$$\text{Data Rate}=1\times 234\times 8\times \frac{5}{6}÷3.6\mu s$$$$=\frac{1\times 234\times 8\times 5}{6\times 3.6\times 10^{-6}}=\frac{9360}{21.6\times 10^{-6}}\approx 433.3\text{Mbps}$$

Wi-Fi 5 (802.11ac): 160 MHz, 8×8 MIMO, 256-QAM, 5/6, Short GI

$$\text{Data Rate}=8\times 468\times 8\times \frac{5}{6}÷3.6\mu s$$$$=\frac{8\times 468\times 8\times 5}{6\times 3.6\times 10^{-6}}=\frac{149760}{21.6\times 10^{-6}}\approx 6933\text{Mbps}\approx 6.93\text{Gbps}$$

Wi-Fi 6 (802.11ax): 160 MHz, 8×8 MIMO, 1024-QAM, 5/6, Short GI

$$\text{Data Rate}=8\times 1960\times 10\times \frac{5}{6}÷13.6\mu s$$$$=\frac{8\times 1960\times 10\times 5}{6\times 13.6\times 10^{-6}}=\frac{784000}{81.6\times 10^{-6}}\approx 9607.8\text{Mbps}\approx 9.6\text{Gbps}$$

Single Spatial Stream Modulation and Coding Scheme

For WiFi4, 802.11n:

MCS Index	Spatial Streams	Modulation Type	Coding Rate	Data Rate (Mbit/s)
				20 MHz Channels		40 MHz Channels
				800 ns GI	400 ns GI	800 ns GI	400 ns GI
0	1	BPSK	1/2	6.5	7.2	13.5	15
1	1	QPSK	1/2	13	14.4	27	30
2	1	QPSK	3/4	19.5	21.7	40.5	45
3	1	16-QAM	1/2	26	28.9	54	60
4	1	16-QAM	3/4	39	43.3	81	90
5	1	64-QAM	2/3	52	57.8	108	120
6	1	64-QAM	3/4	58.5	65	121.5	135
7	1	64-QAM	5/6	65	72.2	135	150

For WiFi5, 802.11ac:

MCS Index	Modulation Type	Coding Rate	Data Rate (Mbit/s)
			20 MHz Channels		40 MHz Channels		80 MHz Channels		160 MHz Channels
			1600 ns GI	800 ns GI	1600 ns GI	800 ns GI	1600 ns GI	800 ns GI	1600 ns GI	800 ns GI
0	BPSK	1/2	4	4	8	9	17	18	34	36
1	QPSK	1/2	16	17	33	34	68	72	136	144
2	QPSK	3/4	24	26	49	52	102	108	204	216
3	16-QAM	1/2	33	34	65	69	136	144	272	282
4	16-QAM	3/4	49	52	98	103	204	216	408	432
5	64-QAM	2/3	65	69	130	138	272	288	544	576
6	64-QAM	3/4	73	77	146	155	306	324	613	649
7	64-QAM	5/6	81	86	163	172	340	360	681	721
8	256-QAM	3/4	98	103	195	207	408	432	817	865
9	256-QAM	5/6	108	115	217	229	453	480	907	961
10	1024-QAM
11	1024-QAM

For WiFi6, 802.11AX

MC Index	Modulation Type	Coding Rate	Data Rate (in Mbit/s)
			20 MHz Channels		40 MHz Channels		80 MHz Channels		160 MHz Channels
			1600 ns GI	800 ns GI	1600 ns GI	800 ns GI	1600 ns GI	800 ns GI	1600 ns GI	800 ns GI
0	BPSK	1/2	8	8.6	16	17.2	34	36.0	68	72
1	QPSK	1/2	16	17.2	33	34.4	68	72.1	136	144
2	QPSK	3/4	24	25.8	49	51.6	102	108.1	204	216
3	16-QAM	1/2	33	34.4	65	68.8	136	144.1	272	282
4	16-QAM	3/4	49	51.6	98	103.2	204	216.2	408	432
5	64-QAM	2/3	65	68.8	130	137.6	272	288.2	544	576
6	64-QAM	3/4	73	77.4	146	154.9	306	324.4	613	649
7	64-QAM	5/6	81	86.0	163	172.1	340	360.3	681	721
8	256-QAM	3/4	98	103.2	195	206.5	408	432.4	817	865
9	256-QAM	5/6	108	114.7	217	229.4	453	480.4	907	961
10	1024-QAM	3/4	122	129.0	244	258.1	510	540.4	1021	1081
11	1024-QAM	5/6	135	143.4	271	286.8	567	600.5	1134	1201