Network Engineering
Bandwidth-Delay Product Calculator
Enter link bandwidth and RTT to compute bandwidth-delay product, required TCP buffer size, and Linux kernel tuning parameters for optimal throughput.
No data is transmitted — everything runs locallyTool
Example — Representative default scenario — bandwidth mbps 200 · rtt ms 40.
BDP
977 KB
200Mbps × 40ms RTT
In-flight data
977 KB
to fully saturate link
Recommended buffer
1,465 KB
1.5× BDP
TCP buffer setting
sysctl net.core.rmem_max=1500000
Linux example
About this tool
Bandwidth-Delay Product Calculator
The Bandwidth-Delay Product Calculator computes BDP, required TCP buffer sizes, and Linux tcp_rmem/tcp_wmem tuning values from bandwidth and RTT.
• Calculate required TCP buffer size for a 10Gbps transatlantic link
• Determine why a high-bandwidth link achieves less throughput than expected
• Compute Linux tcp_rmem and tcp_wmem values for a specific link profile
• Model throughput improvement from increasing TCP buffer size
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FAQ
What does this tool tell you?
The Bandwidth-Delay Product Calculator computes BDP, required TCP buffer sizes, and Linux tcp_rmem/tcp_wmem tuning values from bandwidth and RTT.
What affects the result most?
BDP = bandwidth × RTT — the amount of data in flight to fully utilize a link. TCP buffer sizing: send and receive buffers should be at least BDP to avoid starving the pipe. Example: 1Gbps × 100ms RTT = 12.5MB BDP — need 12.5MB buffers to saturate the link.
How should I use the result?
The calculation is deterministic — the same inputs always produce the same output — so the most useful workflow is to vary one input at a time and see which factor moves the result most. That tells you where to focus your attention before committing to a decision.
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