Inputs
A base link MTU and any combination of tunnel overheads to stack.
AdeOS interactive tools
MTU / MSS Calculator
Work out the real usable MTU and MSS after one or more tunnel encapsulations, and get ready-to-use MSS clamp config.
Loading tool…
Subtract tunnel overhead from a base link MTU and derive the resulting TCP MSS for IPv4 and IPv6.
Outputs
Effective MTU, IPv4/IPv6 MSS, a fragmentation-risk flag, and MSS clamp config snippets.
Example
Check the effective MSS for a WireGuard tunnel over a PPPoE DSL link.
Important note
Results support planning and learning; verify production changes against your platform and change controls.