THE FEUTEX TOOLKIT

TCP Loss Window Reduction

Calculate a Reno-style threshold following loss from the in-flight amount.

Networking workspace● Runs in your browser

01 Your input

Flight sizebytesSender MSSbytes

02 Your result

View or copy raw result data

Result data

Formulassthresh=max(FlightSize/2,2SMSS)

Sources and model references

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

Worked example

Inputs

Flight size: 100000 bytes
Sender MSS: 1460 bytes

Expected results

New slow-start threshold: 50000 bytes
Threshold in segment units: 34.24657534 segments

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

{
  "flight": 100000,
  "mss": 1460
}

Accuracy and scope

Classic RFC 5681 threshold calculation; not a full congestion-control implementation or modern algorithm predictor. 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.