THE FEUTEX TOOLKIT

IPv6 UDP Datagram Budget

Compute nonfragmented application capacity after IPv6 extension headers.

Networking workspace● Runs in your browser

01 Your input

Path MTUbytesIPv6 extension header totalbytesApplication header bytesbytes

02 Your result

View or copy raw result data

Result data

Formulapayload=MTU−40−extensions−8−applicationHeader

Sources and model references

https://www.rfc-editor.org/rfc/rfc8200

Worked example

Inputs

Path MTU: 1280 bytes
IPv6 extension header total: 0 bytes
Application header bytes: 12 bytes

Expected results

Available application payload: 1220 bytes
Application payload fraction: 0.953125 fraction

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

{
  "mtu": 1280,
  "ext": 0,
  "app": 12
}

Accuracy and scope

No fragmentation or jumbograms; entered extension total must already include padding. 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.