How to use the BDP calculator
- Enter the path bandwidth and choose bit/s, Kbit/s, Mbit/s or Gbit/s.
- Enter round-trip time—not one-way delay—and choose milliseconds or seconds.
- Choose decimal SI or binary IEC display for the byte result, then select Calculate.
- Editing clears the old result; a display-unit change after success recalculates immediately.
What bandwidth-delay product means
BDP is bandwidth in bits per second multiplied by round-trip time in seconds. The seconds cancel, leaving an amount of data in bits.
It estimates data that can be in flight before an acknowledgement returns. Divide bits by 8 for bytes.
SI uses powers of 1000 (kB, MB); IEC uses powers of 1024 (KiB, MiB). The underlying byte count is unchanged.
Worked examples
100 Mbit/s × 20 ms = 2,000,000 bits = 250,000 bytes = 250 kB or about 244.14 KiB.
1 Gbit/s × 0 ms = 0 bits. Zero RTT is mathematically valid, though a real remote path normally has positive delay.
Limits
- Bandwidth must be positive; RTT may be zero. Negative, non-finite and scientific-notation inputs are rejected.
- RTT is the complete round trip. Do not double an RTT measurement or substitute one-way delay without converting it.
- The calculator does not measure a connection, tune equipment or promise throughput.
- BDP can inform TCP analysis, but this result alone is not a guaranteed socket or router buffer setting.
Frequently asked questions
Why use RTT instead of one-way delay?
The standard BDP form used for TCP path analysis multiplies bottleneck bandwidth by the acknowledgement round trip.
Why do SI and IEC results differ?
They group the same bytes by 1000 or 1024; no data is added or removed.
Is BDP the speed of my connection?
No. It is an amount of in-flight data calculated from the bandwidth and RTT you provide.