Bandwidth Delay Product Calculator
Compute the bandwidth-delay product: how many bytes are in flight on a link at any instant.
Inputs
Bandwidth Delay Product
7 MiB
Bits In Flight
60,000,000bits
BDP In Kilobytes
7,324.2KB
Packets In Flight
5,000
Window Scale Factor Needed
7
Step by step
Values used
Link bandwidth = 1,000 Mbit/s; Round-trip time = 60 ms; Packet size (MTU) = 1,500 bytes
Bandwidth Delay Product
BDP = bandwidth × RTT, converted from bits to bytes by dividing by 8.
Bandwidth Delay Product
= 7,500,000
Bits In Flight
= 60,000,000 bits
BDP In Kilobytes
= 7,324.2 KB
Packets In Flight
= 5,000
Window Scale Factor Needed
= 7
How it works
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
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.