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Home WiFi Speed Calculator

Convert an advertised WiFi PHY rate into the real TCP throughput you can expect once airtime and overhead are removed.

About Home WiFi Speed Calculator

A WiFi PHY rate is a modulation ceiling, not a throughput figure. Half-duplex media access, preambles, acknowledgements and inter-frame spacing typically leave 45 to 65 per cent of it as usable TCP throughput, and that total is shared between every associated client. Buying a router advertised at 1200 Mbps and measuring 400 Mbps is normal, not a fault — knowing the realistic figure per client is what tells you whether you need another access point.

Formula

Home WiFi Speed

Usable throughput = PHY rate × airtime efficiency × (1 − interference)

PHY rate
Advertised radio rate, shared by all clients
airtime efficiency
Share of airtime carrying payload rather than framing

Worked example

With the default values below, Home WiFi Speed Calculator returns Realistic Aggregate Throughput of 561.00. Change any input above and every figure here is recalculated in your browser.

Inputs used

Advertised PHY rateminimum 1 Mbps
1,200 Mbps
Active clients sharing the radiominimum 1
6
Airtime efficiency after overheadaccepts 0–100 %
55 %
Airtime lost to interference and retriesaccepts 0–100 %
15 %

Results

Realistic Aggregate Throughput
561.00 Mbps
Throughput per Active Client
93.50 Mbps
Aggregate Throughput
70.13 MB/s
Capacity Lost to Overhead
639.00 Mbps
Verdict
Comfortable — every client can stream 4K

Step by step

  1. 1Values used
  2. 2Home WiFi Speed
  3. 3Realistic Aggregate Throughput= 561.00 Mbps
  4. 4Throughput per Active Client= 93.50 Mbps
  5. 5Aggregate Throughput= 70.13 MB/s
  6. 6Capacity Lost to Overhead= 639.00 Mbps
  7. 7Verdict= Comfortable — every client can stream 4K

Assumptions and limits

  • The result is derived only from the 4 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 Home WiFi Speed calculated?

Usable throughput = PHY rate × airtime efficiency × (1 − interference) A WiFi PHY rate is a modulation ceiling, not a throughput figure. Half-duplex media access, preambles, acknowledgements and inter-frame spacing typically leave 45 to 65 per cent of it as usable TCP throughput, and that total is shared between every associated client.

Why does Home WiFi Speed matter?

Buying a router advertised at 1200 Mbps and measuring 400 Mbps is normal, not a fault — knowing the realistic figure per client is what tells you whether you need another access point.

What values do I need to enter?

This calculator takes 4 inputs: Advertised PHY rate, Active clients sharing the radio, Airtime efficiency after overhead, Airtime lost to interference and retries. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.

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