Wireless Throughput Calculator
Model real Wi-Fi cell throughput with airtime fairness, so slow legacy clients drag the whole cell down the way they do in practice.
About Wireless Throughput Calculator
Wi-Fi schedules airtime, not bits, so a client at 65 Mbps occupies thirteen times the airtime of one at 866 Mbps for the same payload. Combining the rates as a harmonic mean weighted by airtime share gives the rate the cell actually achieves, and MAC overhead removes a further third of it. This is why one old handheld can halve a modern cell's throughput, and why removing 802.11b/g data rates is usually the cheapest Wi-Fi performance fix available.
Formula
Wireless Throughput
airtime-weighted rate = 1 ÷ Σ(airtime share ÷ PHY rate); usable throughput = that rate × MAC efficiency.
- airtime share
- Fraction of transmit opportunities a client group consumes
- MAC efficiency
- Throughput left after preambles, ACKs, contention and retries
Worked example
With the default values below, Wireless Throughput Calculator returns Usable Cell Throughput of 162.5. Change any input above and every figure here is recalculated in your browser.
Inputs used
- PHY rate of modern clientsaccepts 1–20,000 Mbps
- 866 Mbps
- PHY rate of slow legacy clientsaccepts 1–5,000 Mbps
- 65 Mbps
- Airtime share taken by slow clientsaccepts 0–100 %
- 20 %
- MAC efficiency after protocol overheadaccepts 20–95 %
- 65 %
- Active clients in the cellaccepts 1–500 clients
- 20 clients
Results
- Usable Cell Throughput
- 162.5 Mbps
- Airtime-Weighted PHY Rate
- 250.0 Mbps
- Throughput per Client
- 8.12 Mbps
- Degradation Caused by Slow Clients
- 71.1%
Step by step
- 1Values used
- 2Wireless Throughput
- 3Usable Cell Throughput= 162.5 Mbps
- 4Airtime-Weighted PHY Rate= 250.0 Mbps
- 5Throughput per Client= 8.12 Mbps
- 6Degradation Caused by Slow Clients= 71.1
Assumptions and limits
- The result is derived only from the 5 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
- Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Frequently Asked Questions
How is Wireless Throughput calculated?
airtime-weighted rate = 1 ÷ Σ(airtime share ÷ PHY rate); usable throughput = that rate × MAC efficiency. Wi-Fi schedules airtime, not bits, so a client at 65 Mbps occupies thirteen times the airtime of one at 866 Mbps for the same payload. Combining the rates as a harmonic mean weighted by airtime share gives the rate the cell actually achieves, and MAC overhead removes a further third of it.
Why does Wireless Throughput matter?
This is why one old handheld can halve a modern cell's throughput, and why removing 802.11b/g data rates is usually the cheapest Wi-Fi performance fix available.
What values do I need to enter?
This calculator takes 5 inputs: PHY rate of modern clients, PHY rate of slow legacy clients, Airtime share taken by slow clients, MAC efficiency after protocol overhead, Active clients in the cell. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.