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MTU / MSS Calculator

Model encapsulation stacks, Ethernet wire cost and practical TCP MSS commands for common platforms.

Runs locally in your browser

PATH MTU

Path MTU / MSS

Start with the outer IP MTU and subtract up to 16 ordered encapsulation layers.

Optional. A visible placeholder is used when empty.
Encapsulation stack

Path result

1500

No encapsulation layers. Add one or calculate the base MTU.

ETHERNET L2

Ethernet / L2 on-wire

Add headers, tags, labels, FCS, preamble/SFD and inter-frame gap to an IP payload.

Frame and wire result

L2

Add headers, tags, labels, FCS, preamble/SFD and inter-frame gap to an IP payload.

Official command references