TCP Throughput Calculator

- SWITCH.ch is the Swiss national research and education network (NREN), analogous to Internet2 in the US or Jisc in the UK. It provides high-speed connectivity to universities, labs, and other research institutions across Switzerland. - This page is a simple but practical networking tool: it calculates the maximum possible TCP throughput given a link's bandwidth (capacity) and round-trip time (latency), using the standard formula: Throughput ≤ (TCP Window Size) / (RTT). It accounts for the TCP receive window (often the bottleneck in long-distance links). - Why it matters: Network engineers and system administrators use this to diagnose whether poor performance is due to network limits (latency × bandwidth) rather than misconfiguration. It's especially relevant for research networks moving large datasets between continents (e.g., CERN in Geneva to US labs), where high bandwidth but high latency ("long fat pipes") requires careful TCP tuning to fill the pipe.