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THE FEUTEX TOOLKIT

IPv4 Fragmentation Layout

Compute fragment count, aligned fragment payload and final fragment size.

Networking workspace● Runs in your browser
01 Your input
02 Your result
View or copy raw result data
FormulanonfinalPayload=8floor((MTU−header)/8)
Sources and model references

Worked example

Inputs

IP payload bytes
4000 bytes
Path MTU
1500 bytes
IP header bytes
20 bytes

Expected results

Full-fragment payload
1480 bytes
Fragment count
3 fragments
Last IP fragment size
1060 bytes

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

How to use this tool

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

Try this example

{
  "payload": 4000,
  "mtu": 1500,
  "header": 20
}

Accuracy and scope

Fragmentation permitted, identical header size in each fragment, no differing copied options. 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.