Bandwidth-Delay Product Calculator

About this calculator

The bandwidth-delay product (BDP) is the amount of data "in flight" on a network link at any moment: BDP = bandwidth × round-trip time (RTT). It represents the maximum amount of unacknowledged data that can be in transit before the sender must wait for an acknowledgment, and it defines the ideal TCP send/receive window size needed to fully utilize the link's capacity.

If a TCP window is smaller than the BDP, the connection can't fill the "pipe" and throughput suffers regardless of available bandwidth — this is exactly why long-distance, high-bandwidth links (like satellite or transcontinental fiber) need window scaling enabled to reach their theoretical speed, a problem known as the "long fat network" (LFN) problem.

Network engineers tuning TCP window sizes and buffer configurations, systems administrators diagnosing why a high-bandwidth link isn't reaching expected throughput, and students studying computer networking all use this calculation to find the BDP from a link's bandwidth and latency.