Free tool
Is that IMO number written correctly?
An IMO number is seven digits, and the seventh is a check digit. If it does not hold, the number has been mistyped — a transposed digit in a charter recap, a class notification or a port declaration shows up here in one second. Nothing leaves your browser.
One per line. «IMO», spaces and hyphens are fine.
Enter a number to see the result.
How the check digit works
The first six digits are multiplied by 7, 6, 5, 4, 3 and 2. The products are summed, and the last digit of that sum must equal the seventh digit. The tool shows the full calculation, so you can see exactly where it breaks.
What the number does not tell you
Ship name and flag state are not encoded in the number. IMO numbers are assigned in sequence, not by nationality, and the number stays with the hull through renamings and flag changes. So we do not guess: name, flag and ownership must be looked up in a register. These are public:
More than one vessel to keep straight?
The same check runs when you register a vessel in Justera Maritime, where name, flag, class society, certificate dates and events sit together per vessel — validated once, kept with a history.
Norsk versjon: IMO-sjekker