TCP Throughput (Latency & Packet Loss)

Estimate the maximum TCP speed over a connection from its round-trip time, packet loss and window size, free online.

MSS (bytes)

Round-trip time (ms)

Packet loss (%)

TCP window (KB)

Line speed (Mbps)

About this calculator

Two limits apply. The Mathis formula gives a loss-limited rate ≈ (MSS ÷ RTT) × (1.22 ÷ √p). The window limit is window size ÷ RTT. The real throughput is the smaller of the two (and of your line speed). High latency and even 0.1% loss sharply cut a single TCP flow.