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TCP Throughput Calculator

Calculate the maximum achievable TCP throughput based on your link bandwidth and round-trip time. Useful for understanding why your backup transfers may not saturate your connection.

Your available upload bandwidth
ms
Latency to the remote server (use ping to measure)
Auto-tuned to 244 KB (BDP capped at 6 MB)

TCP Throughput Results

Max TCP Throughput

100 Mbit/s
Single TCP stream

Bandwidth-Delay Product

244 KB
Required window size

Link Utilization

100.0%
Of available bandwidth

4 MB File Transfer

336 ms
At max TCP throughput

Streams to Saturate Link

1
Parallel TCP connections
With Linux auto-tuning, your system will adjust the TCP window to fully saturate this link. No manual tuning needed.

How it works

A single TCP connection can only have a limited amount of data "in flight" at any time, determined by the TCP window size. The maximum throughput of one TCP stream is:

Throughput = TCP Window Size / RTT

The Bandwidth-Delay Product (BDP) tells you the minimum TCP window size needed to fully utilize your link:

BDP = Bandwidth × RTT

If your TCP window is smaller than the BDP, throughput is window-limited, not bandwidth-limited. Most Linux systems auto-tune the window up to net.ipv4.tcp_rmem / net.ipv4.tcp_wmem max values.