Protocol calculator
Wi-Fi Data Rate Calculator
802.11n/ac/ax/be PHY rate, OFDM symbol values, and estimated single-link MAC goodput.
Free browser-side calculator for 802.11n/ac/ax/be whole-channel single-user links. Enter MCS, channel width, spatial streams, guard interval, and frame settings to calculate PHY rate, frame airtime, and estimated MAC goodput. Inputs are not uploaded. RU/MRU, MLO, contention, retries, and packet error rate are outside this model.
802.11 MCS and airtime rate
Calculate the PHY rate first, then estimate single-link MAC goodput with editable airtime overhead.
Advanced MAC goodput settings
- PHY rate
- 1.201 Gbps
- Estimated MAC goodput
- 518.5 Mbps
- Airtime efficiency
- 43.2%
- Modulation / coding
- 1024-QAM · 5/6
- Data subcarriers
- 980
- Data bits / OFDM symbol
- 16,333.33 bits
- OFDM symbol duration
- 13.6 µs
- Exchange time
- 370.3 µs
Goodput is a single-sender airtime estimate with no collisions or retries, not a speed-test prediction.
How the 802.11 PHY rate is calculated
An MCS index selects the modulation and forward-error-correction coding rate. Channel width selects the number of
data subcarriers, spatial streams multiply the parallel payload, and the guard interval changes the OFDM symbol
duration. The calculator applies PHY rate = data bits per OFDM symbol / OFDM symbol duration.
This is a formula calculator, not only a Wi-Fi MCS table. It exposes the modulation, coding rate, data-subcarrier count, data bits per OFDM symbol, and symbol duration behind the final Mbps or Gbps result.
Supported Wi-Fi generations
| Generation | MCS | Channel width | GI | Max NSS |
|---|---|---|---|---|
| 802.11n / HT | 0-7 | 20, 40 MHz | 0.4, 0.8 µs | 4 |
| 802.11ac / VHT | 0-9 | 20-160 MHz | 0.4, 0.8 µs | 8 |
| 802.11ax / HE | 0-11 | 20-160 MHz | 0.8, 1.6, 3.2 µs | 8 |
| 802.11be / EHT | 0-13 | 20-320 MHz | 0.8, 1.6, 3.2 µs | 16 |
HT is entered as MCS 0-7 plus a separate NSS value. This avoids the older combined HT numbering where MCS 8-15, 16-23, and 24-31 encode two, three, and four streams. Legacy 802.11a/b/g rates are outside this calculator because they do not use the same MCS-and-NSS input model. VHT defines MCS 0-9, but some MCS, channel-width, and NSS tuples are undefined; the calculator rejects those combinations instead of inventing a rate.
Rate-table sources: Cisco 802.11ac and later data-rate tables and Cisco 802.11n MCS reference.
Worked 802.11ax MCS 11 example
For 802.11ax HE, MCS 11 means 1024-QAM with a 5/6 coding rate. An 80 MHz full-bandwidth transmission uses 980 data
subcarriers. With two spatial streams, one OFDM symbol carries
980 × 10 × 5/6 × 2 = 16,333.33 data bits. The HE symbol lasts
12.8 + 0.8 = 13.6 µs, so the PHY rate is approximately 1201 Mbps.
Selecting a longer guard interval lowers the raw rate because each symbol carries the same data over more airtime. Selecting more spatial streams increases the rate only when both endpoints and the radio channel can sustain those independent streams.
Example reference: Cisco Wi-Fi data-rate tables.
How the MAC goodput estimate works
The advanced panel estimates one contention-based exchange: DIFS or AIFS, average backoff, the data PPDU, SIFS, and the ACK or Block ACK. It includes a 30-byte MAC-header assumption, a 4-byte FCS, A-MPDU delimiters and padding, OFDM symbol rounding, and an editable ACK PHY rate. Delivered payload bits divided by the full exchange time gives the estimated MAC goodput. Combinations that would exceed the 5,484 µs data-PPDU duration limit are rejected instead of being presented as one impossible transmission.
Airtime model: IEEE 802.11 throughput and airtime reference.
Preamble duration is editable because it depends on PPDU format, training fields, and spatial-stream configuration. The defaults are useful for comparison, but measured preamble and control-rate values are better when validating a particular chipset or capture.
What this result does not predict
The estimate assumes one sender, no collisions, no retries, one selected MCS, and a full-width single-user channel. It does not model OFDMA RU or MRU allocation, multi-link operation, puncturing, DCM, rate adaptation, packet error, hidden nodes, competing clients, TCP behavior, or application overhead. Use it for link-budget reasoning, MCS-table checks, airtime comparison, and lab planning—not as a promise of internet speed.
Frequently asked questions
Why is Wi-Fi throughput lower than the PHY rate?
PHY rate is the raw coded data rate. A real exchange also spends airtime on preambles, MAC headers, contention, SIFS or DIFS, ACK frames, retransmissions, other stations, and rate changes. This page estimates a clean single-sender exchange, so measured throughput can still be lower.
Is the number of spatial streams the same as the antenna count?
No. NSS is the number of independently coded spatial streams used for this link. A radio can have more physical antennas than active spatial streams, while the link is also limited by the capability of the other endpoint and the radio channel.
Which Wi-Fi generations and MCS ranges are supported?
The calculator supports 802.11n HT MCS 0-7, 802.11ac VHT MCS 0-9, 802.11ax HE MCS 0-11, and 802.11be EHT MCS 0-13. It uses an explicit NSS input instead of the combined legacy HT MCS 0-31 numbering. Some VHT MCS, channel-width, and NSS tuples are undefined and are rejected.
Why are some 802.11ac VHT combinations invalid?
VHT defines MCS 0-9, but not every MCS is valid for every channel width and spatial-stream count. The calculator checks the VHT rate table and rejects undefined tuples instead of returning a misleading rate.
Does this Wi-Fi MCS calculator support OFDMA resource units?
No. The current calculator models a full-bandwidth single-user PHY. It does not calculate RU or MRU allocations, DCM, puncturing, multi-link operation, or per-user OFDMA scheduling.
What do SIFS, DIFS, slot time, and backoff change?
They add channel-access and response time around the data transmission. SIFS separates data from its ACK, while DIFS or AIFS and random backoff delay a new contention-based transmission. These values affect estimated MAC goodput but not the PHY rate.
Should I use ACK or Block ACK for an aggregated transmission?
Use Block ACK for an A-MPDU with more than one MPDU. The calculator rejects a multi-frame aggregate paired with a normal ACK because that combination does not describe the modeled A-MPDU exchange.