MTU / MSS Calculator
Estimate TCP MSS after IP/TCP headers and optional tunnel overhead.
Troubleshooting
For a VPN, add the real tunnel overhead and validate the result with packet-size testing to avoid fragmentation and incorrect MSS clamping.
Questions about this tool
Which inputs have the greatest effect on MTU/MSS calculation?
Use measured or documented values, keep units consistent and include the operational margin that the production environment actually needs.
Is the calculated value a final sizing recommendation?
No. It is a planning baseline; vendor limits, redundancy, peaks, growth and environmental constraints still need to be applied.
How should I validate the result?
Compare it with a real measurement, vendor specification or existing workload before purchasing or changing production capacity.