Bandwidth-Delay Product

The bandwidth-delay product tells you how much data can be occupying a communication path at once when the link is being kept busy. It comes from multiplying the rate at which bits can be put onto the link by the time a round trip takes, so the units work out as bits/s × s = bits. A larger RTT means more data can be "in flight" before any feedback arrives, while a larger bandwidth means more data can be launched each second.

Use this when analyzing network utilization, TCP window sizing, or whether a path is being underfilled due to latency. It is especially useful in high-speed, long-distance, or satellite links where delay can dominate throughput.

• Using one-way latency instead of round-trip time
• Forgetting to convert milliseconds to seconds before multiplying
• Mixing units such as Mbps and MB without converting consistently