Bandwidth-Delay Product Window Calculator

Method, formula and assumptions

BDP bytes = target bits per second x RTT seconds / 8. Window-limited bits per second = available window bytes x 8 / RTT. KiB uses 1,024 bytes.

Input definitions and supported units

• Target throughput (Mb/s): Measured or assumed numerical value, from 0 to 1000000; zero is supported where the stated method permits it.
• Round-trip time (ms): Measured or assumed numerical value, from 0.001 to 100000; must be positive.
• Available in-flight window (KiB): Measured or assumed numerical value, from 0 to 1000000000; zero is supported where the stated method permits it.

Worked example with answer

100 Mb/s with 80 ms RTT has a 1 MB BDP, or 976.5625 KiB. A 512 KiB window limits this ideal model to 52.4288 Mb/s and is 464.5625 KiB short of the target.

How to use the results

This exposes a flow-control window bottleneck separately from raw link rate. It is not a recommendation to override operating-system socket settings blindly.

Results retain full precision internally and display up to four decimal places. Very small nonzero results use scientific notation rather than appearing as zero. Check the labels before comparing values across units.

Limitations and references

Congestion control, packet loss, application stalls and bandwidth variation can limit throughput well below this window-only bound.

The method is a self-contained arithmetic, geometric or explicitly stated mathematical model. There are no imported tariffs, empirical presets or equipment specifications; measured values and allowances must come from your own process.

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