Convert an advertised WiFi PHY rate into the real TCP throughput you can expect once airtime and overhead are removed.
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.
Home WiFi Speed
Usable throughput = PHY rate × airtime efficiency × (1 − interference)
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.
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.
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.