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TCP Flag Calculator

v1.2.1

Decode TCP flag bitmasks and identify common packet flag combinations.

Decodes TCP flag bitmasks into human-readable flag names (SYN, ACK, FIN, RST, PSH, URG, ECE, CWR) and identifies common packet patterns like handshakes, resets, and data transfers.

How to use
  • →Enter a decimal or hexadecimal TCP flags value to decode.
  • →Or toggle individual flag checkboxes to build a bitmask and see the value.
  • →Useful for reading tcpdump/Wireshark output and understanding TCP state machine transitions.

Quick Presets

TCP Flags

Calculated Value

Decimal

0

Hexadecimal

0x000

Binary (9-bit)

000000000

Reverse Lookup

Enter a decimal or hex value to see which flags are set.