Bandwidth delay product calculator
Estimate in-flight data from bandwidth and round-trip time, with an optional receive-window comparison.
Bandwidth multiplied by round-trip time estimates the data in flight. Eight bits make one byte; decimal and binary prefixes are distinct. The whole-byte result rounds upward. An optional receive window gives a theoretical throughput ceiling. Zero round-trip time has no finite window-derived ceiling. Results that exceed precise whole-byte representation are rejected. This does not measure throughput, losses or congestion control and is not a router buffer sizing recommendation. Runs locally without uploads. Limit: 500000 combined input characters, 1000 services and 5000 conflicting pairs. Complete JSON and JSON Pointer CSV exports are each capped at 2000000 characters; CSV contains at most 200000 typed values. Preview shows at most 200 rows. Calculations stop after 10 seconds. Downloads retain your source inputs, units, assumptions and complete results. Up to 500,000 characters. Review the settings before running.
Your result
How to use Bandwidth delay product calculator
- Enter bandwidth and select its bit or byte unit.
- Enter round-trip time, select its unit and optionally enter a receive window in bytes.
- Compare the in-flight data estimate and window limit, then download the complete report.
Useful next steps
Use round-trip time and explicit units
At 100 Mbps and 50 ms round-trip time, the bandwidth-delay product is 5000000 bits or 625000 bytes. One byte contains eight bits. Decimal prefixes such as MB and binary prefixes such as MiB are different; the selected units control the calculation.
A window ceiling is not measured throughput
The optional receive-window ceiling divides window bytes by round-trip seconds and converts to bits per second. Actual throughput can also be limited by congestion control, loss, overhead and application behavior. A zero round-trip time has no finite window-derived ceiling. This estimate is not router buffer sizing advice.