IMO Number Validator
An IMO number is a unique seven-digit identifier assigned to every seagoing commercial vessel by the International Maritime Organization. Enter an IMO number below to validate it using the official check digit algorithm and look up the vessel in our database of 96,000+ ships.
Frequently Asked Questions
What is an IMO number?
An IMO number is a unique seven-digit identifier assigned by the International Maritime Organization to every seagoing vessel of 100 gross tonnage and above. It remains with the vessel for its entire lifetime, regardless of changes in name, flag, or ownership. IMO numbers were introduced in 1987 under the SOLAS Convention to improve maritime safety and reduce fraud.
How is the IMO check digit calculated?
The IMO check digit is the last of the seven digits. To validate it, multiply digits 1 through 6 by the weights 7, 6, 5, 4, 3, 2 respectively, then sum the results. The check digit must equal the last digit of that sum. For example, for IMO 9074729: (9x7)+(0x6)+(7x5)+(4x4)+(7x3)+(2x2) = 63+0+35+16+21+4 = 139. The last digit of 139 is 9, which matches the check digit.
How many vessels have IMO numbers?
There are approximately 96,000 active commercial vessels with IMO numbers in VesselScore's database. The total number of IMO numbers ever issued is higher, as it includes vessels that have been scrapped, lost, or laid up. The Lloyd's Register - IHS Markit Ship Information Database maintains the authoritative registry.
Can an IMO number change?
No. Once assigned, an IMO number stays with the vessel permanently. It does not change when the vessel is renamed, reflagged, or sold to a new owner. This is by design, as the IMO scheme exists specifically to provide a permanent identification that cannot be altered to obscure a vessel's history.
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