Bandwidth Delay Product and TCP Window Calculator
Estimate in-flight data and a receive-window throughput ceiling using entered path bandwidth and round-trip time.
YOUR CALCULATION
Result
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Calculation steps
Work through one step at a time or reveal the complete calculation. The steps use your current inputs.
How to calculate
Multiply bottleneck bandwidth by round-trip time to estimate required in-flight bits. Divide the effective receive window by RTT for its ideal throughput ceiling, capped by the entered bandwidth.
BDP bits=bandwidth bit/s×RTT seconds; receive-window ceiling=window bits/RTT
Worked example
100 Mbit/s and 100 ms RTT give 10 million bits, or 1.25 MB, in flight. A 64 KiB effective receive window limits the ideal rate to 5.24288 Mbit/s.
Assumptions and input details
RTT is round-trip, not one-way latency. Enter the effective window after scaling, not the raw 16-bit field. This receive-window bound omits congestion window, slow start, loss, retransmissions, protocol overhead, application limits and path changes. Segment count rounds BDP bytes up by the entered payload bytes; it is not packet capture or recommended buffer tuning.
References: IETF RFC 7323: bandwidth-delay product and windows
Unit definitions
Unit selection is independent of language. Each selector contains only units for its physical quantity. Calculations use defined base units internally.
One byte is eight bits. Decimal prefixes (k, M, G, T, P, E) use powers of 1000. Binary prefixes (Ki, Mi, Gi, Ti, Pi, Ei) use powers of 1024. Transfer rates are per second.
Using this calculator
Can I enter my own problem?
Yes. Replace the example values with your own inputs. The result, calculation steps, tables and applicable diagrams update from those inputs. Blank or invalid values clear the result; example values are never silently substituted for missing inputs.
Are the results exact?
Results use floating-point arithmetic and displayed rounding. Read the formula, assumptions and any stated data precision before interpreting the result.
Is my input uploaded?
The calculation runs in your browser. No account, file upload or external AI service is required. Inputs are not saved between page reloads.
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