TCP Throughput
Calculate theoretical TCP throughput using the Mathis formula
How to use TCP Throughput
- 1Enter the RTT (round-trip time) and packet loss probability.
- 2Enter the MSS (maximum segment size, usually 1460 bytes).
- 3Read the maximum sustainable TCP throughput for that path.
TCP throughput (Mathis equation)
Throughput ≤ (MSS / RTT) × C / √(loss), C ≈ 0.93The Mathis equation models the throughput ceiling of a TCP connection limited by packet loss and round-trip time.
Even tiny loss (e.g., 0.1%) caps throughput dramatically on long-RTT links, which is why high-loss satellite and WAN links feel slow.
Frequently asked questions
Why does 1% loss hurt so much?
Throughput scales with 1/√loss, so 1% loss can cut capacity to about 10% of the loss-free case.
Does a bigger window help?
Only up to the BDP; loss still caps the Mathis ceiling regardless of window size.
How do I improve it?
Reduce RTT or loss (better path, FEC, TCP variants like BBR) rather than just raising bandwidth.