Bandwidth Delay Product Calculator
Compute the bandwidth-delay product: how many bytes are in flight on a link at any instant.
About Bandwidth Delay Product Calculator
The product of rate and delay is the amount of data the path holds — the volume that has left the sender but has not yet been acknowledged. Dividing it by the MTU gives the packet count the path stores. The BDP is the single number that sizes TCP windows, socket buffers and switch buffers; anything smaller than it leaves the link idle waiting for acknowledgements.
Formula
Bandwidth Delay Product
BDP = bandwidth × RTT, converted from bits to bytes by dividing by 8.
- bandwidth
- Link rate in bits per second
- RTT
- Round-trip time in seconds
- BDP
- Bytes in flight on the path
Worked example
With the default values below, Bandwidth Delay Product Calculator returns Bandwidth Delay Product of 7 MiB. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Link bandwidthminimum 0.1 Mbit/s
- 1,000 Mbit/s
- Round-trip timeminimum 0.1 ms
- 60 ms
- Packet size (MTU)accepts 68–9,216 bytes
- 1,500 bytes
Results
- Bandwidth Delay Product
- 7 MiB
- Bits In Flight
- 60,000,000 bits
- BDP In Kilobytes
- 7,324.2 KB
- Packets In Flight
- 5,000
- Window Scale Factor Needed
- 7
Step by step
- 1Values used
- 2Bandwidth Delay Product
- 3Bandwidth Delay Product= 7,500,000
- 4Bits In Flight= 60,000,000 bits
- 5BDP In Kilobytes= 7,324.2 KB
- 6Packets In Flight= 5,000
- 7Window Scale Factor Needed= 7
Assumptions and limits
- The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
- Figures are rounded for display to 1 decimal place, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Frequently Asked Questions
How is Bandwidth Delay Product calculated?
BDP = bandwidth × RTT, converted from bits to bytes by dividing by 8. The product of rate and delay is the amount of data the path holds — the volume that has left the sender but has not yet been acknowledged. Dividing it by the MTU gives the packet count the path stores.
Why does Bandwidth Delay Product matter?
The BDP is the single number that sizes TCP windows, socket buffers and switch buffers; anything smaller than it leaves the link idle waiting for acknowledgements.
What values do I need to enter?
This calculator takes 3 inputs: Link bandwidth, Round-trip time, Packet size (MTU). The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.
Is a bigger buffer always better?
No. Buffers much larger than the BDP cause bufferbloat: packets queue instead of being dropped, latency climbs and loss-based congestion control loses its feedback signal. Target the BDP, not a multiple of it.