THE FEUTEX TOOLKIT

Ideal TCP Slow-Start Rounds

Estimate RTT rounds to grow an initial congestion window to a target.

Networking workspace● Runs in your browser

01 Your input

Initial windowsegmentsTarget windowsegmentsRTTs

02 Your result

View or copy raw result data

Result data

Formularounds=ceil(log₂(target/initial))

Sources and model references

https://www.rfc-editor.org/rfc/rfc5681

Worked example

Inputs

Initial window: 10 segments
Target window: 160 segments
RTT: 0.05 s

Expected results

Growth rounds: 4 RTTs
Growth time: 0.2 s

Load the example in the workspace to reproduce these results. Display rounding does not change the underlying calculation.

How to use this tool

Enter the labeled inputs in the indicated units.
Calculate and compare every output against the stated model assumptions.

Try this example

{
  "initial": 10,
  "target": 160,
  "rtt": 0.05
}

Accuracy and scope

Ideal doubling each RTT with acknowledgments for all segments; excludes delayed ACK, losses and slow-start threshold. Simplified analytical model; not a design recommendation or safety certification.

Is my data uploaded?

This tool runs locally in your browser. Input and output are not sent to a processing server. Copy or download your result before leaving the page.