FREE · NETWORK & IT INFRASTRUCTURE
TCP Throughput & Latency Calculator.
Calculate the bandwidth-delay product, the TCP window needed and the throughput limited by window size, latency and packet loss.
64 KiB is the maximum without window scaling (RFC 7323).
- Bandwidth-delay product
- 10 MB Data in flight needed to fill the link
- Window needed per stream
- 9,766 KiB
- Window scale shift needed
- 8
- Window-limited throughput
- 6.55 Mbps
- Loss-limited (Mathis model)
- No loss entered
- Link utilisation
- 0.7 %
- Time for the file
- 3.4 h
Same window at other distances
| RTT | Window-limited throughput | With this loss |
|---|---|---|
| 1 ms | 524.29 Mbps | 524.29 Mbps |
| 5 ms | 104.86 Mbps | 104.86 Mbps |
| 10 ms | 52.43 Mbps | 52.43 Mbps |
| 20 ms | 26.21 Mbps | 26.21 Mbps |
| 40 ms | 13.11 Mbps | 13.11 Mbps |
| 80 ms | 6.55 Mbps | 6.55 Mbps |
| 150 ms | 3.5 Mbps | 3.5 Mbps |
| 300 ms | 1.75 Mbps | 1.75 Mbps |
- Mathis et al. (1997) estimates loss-limited throughput for Reno-style congestion control: MSS ÷ RTT × 1.22 ÷ √loss. CUBIC and BBR behave differently, BBR especially under random loss.
- Linux auto-tunes windows up to net.ipv4.tcp_rmem / tcp_wmem maxima; Windows uses receive-window auto-tuning.
How to use TCP Throughput & Latency Calculator
Enter link speed, round-trip time, window size, packet loss, MSS and streams. Compare throughput at other distances and the time to transfer a file.
How it works
Window-limited throughput = window ÷ RTT per stream. Loss-limited throughput = MSS ÷ RTT × 1.22 ÷ √loss. The achievable rate is the smallest of those and the link speed; BDP = bandwidth × RTT.
Example
A 64 KiB window over 80 ms caps one TCP stream at 6.55 Mbps; filling 1 Gbps needs a 9.5 MiB window.
Questions about TCP Throughput & Latency Calculator
Is TCP Throughput & Latency Calculator free, and do I need an account?
Yes. This tool is free to use in your browser without an account. Processing takes place on your device.
What are the limits and what should I check?
The loss model (Mathis et al.) describes Reno-style congestion control; CUBIC and BBR behave differently. Everything is calculated in your browser; nothing is sent or probed on the network. Review the result before using it in your work.
Is my input sent to a server?
Your input is processed in your browser and is not uploaded by this tool. Files and pasted text are cleared when the page is refreshed. Normal website requests are still required to load the page and its libraries. Read the privacy explanation.