Why is standard Ethernet MSS 1460?

Standard Ethernet MTU is 1500 bytes; subtracting a minimal 20-byte IP header and 20-byte TCP header leaves 1460 bytes for actual application data — the most common MSS value seen in packet captures.

Do IP options or TCP options change this?

Yes, IP or TCP options (like timestamps) add extra header bytes beyond the 20-byte minimum, further reducing the effective MSS — enter the actual header sizes if options are in use.

MSS (Maximum Segment Size) Calculator

Calculate the Maximum Segment Size (MSS) — the largest amount of TCP payload data that can fit in a single packet — by subtracting IP and TCP header overhead from the network's Maximum Transmission Unit (MTU).

Inputs

Results

Maximum Segment Size (MSS): 1,460

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Formula

MSS = MTU − IP Header Size − TCP Header Size

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