TCP Bandwidth Delay Product Calculator
Use this TCP bandwidth delay product calculator to estimate the TCP receive window needed to fill a link across a given round-trip time.
Updated May 2026No signup requiredMobile friendly
Calculator
Enter your values, then choose Calculate.
How to use this calculator
Enter the planning values that match your network, storage, or cloud scenario. Use realistic production assumptions when sizing anything that affects availability, performance, or cost.
Formula or calculation method
Bandwidth delay product equals bandwidth in bits per second multiplied by round-trip time in seconds, then divided by 8 to show bytes.
Worked example
A 1,000 Mbps path with 40 ms RTT needs about 4.77 MB of TCP window to keep the pipe full with one stream.
Practical planning tips
- WAN tuning.
- Backup replication planning.
- Long-distance file transfer estimates.
Common mistakes to avoid
- Using one-way latency instead of round-trip time.
- Ignoring packet loss and application limits.
- Assuming a larger window fixes every slow transfer.
FAQ
Frequently asked questions
Is this the same as speed test throughput?
No. It estimates window size needed to use the path, not actual measured throughput.
Do parallel streams change the total BDP?
No. They split the needed window across streams.
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