Free Tool
Vessel Identifier Checker
Validate an IMO number's check digit, and decode an MMSI to the issuing flag — data-entry sanity checks for documents and fixtures.
IMO number checksum
VALIDIMO 9074729
9computed check digit (actual: 9)
Check digit = units digit of d₁·7 + d₂·6 + d₃·5 + d₄·4 + d₅·3 + d₆·2 — must equal the seventh digit (IMO scheme).
MMSI → flag decode
366MID (maritime identification digits)
United Statesissuing administration / flag
MID assignments per ITU M.1180. This decodes the flag — it is not a live vessel lookup and reveals nothing about position or activity.
Scope
Validation — not a live ship database.
IMO checksum
The seventh digit is computed from the first six — catches typos in charters, B/Ls and ISPS docs.
MMSI → MID
First three digits identify the issuing administration per ITU M.1180.
Not AIS
Identifiers validate/decode — they reveal nothing about position, activity or particulars.
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Port data is the other half.
The port directory covers 5,410 facilities with positions and limits.