Tools · MMSI decoder
MMSI decoder
Nine digits in, plain English out: what kind of station the number belongs to, where its country digits sit, and the registry they point to. Nothing is sent anywhere — it runs in your browser.
Result
How the decoder reads an MMSI
A Maritime Mobile Service Identity is nine digits, and the first few decide everything else. The decoder checks the prefixes in the order the ITU defines them — the most specific first — and only then reads the Maritime Identification Digits (MID) from the position that format puts them in:
| Pattern | Station | Country digits |
|---|---|---|
| MIDxxxxxx | Ship station | Digits 1 to 3 |
| 00MIDxxxx | Coast station | Digits 3 to 5 |
| 0MIDxxxxx | Group of ships | Digits 2 to 4 |
| 111MIDxxx | SAR aircraft | Digits 4 to 6 |
| 99MIDxxxx | Aid to navigation | Digits 3 to 5 |
| 98MIDxxxx | Craft associated with a parent ship | Digits 3 to 5 |
| 970xxyyyy | AIS-SART (search and rescue transmitter) | None — xx is the manufacturer, yyyy a serial |
| 972xxyyyy | Man-overboard device | None — xx is the manufacturer, yyyy a serial |
| 974xxyyyy | EPIRB with AIS | None — xx is the manufacturer, yyyy a serial |
| 8MIDxxxxx | Handheld VHF with DSC and GNSS | Digits 2 to 4 |
Only a ship station carries its flag in the first three digits. An MMSI says which administration issued the number — not who owns the vessel, where it trades or where it is now — and a ship that reflags gets a new one. For the full background, read Reading an MMSI. To check a ship’s permanent identity instead, use the IMO number checker.