Check seven-digit ship identifier checksums.
Initialising algorithm engine for IMO Ship Number Calculator...
How IMO Ship Number Calculator Works?
The IMO Ship Number Calculator works by multiplying the first 6 digits of the 7-digit International Maritime Organization (IMO) number by weights 7 down to 2 and using the last digit of the sum as the check digit.
- 1Enter the first 6 digits of the IMO number.
- 2Multiply the digits by 7, 6, 5, 4, 3, and 2.
- 3Add the products.
- 4Take the rightmost digit of the sum as the 7th digit.
IMO Ship Number Calculator Formula
The IMO number formula is d₇ = (7d₁ + 6d₂ + 5d₃ + 4d₄ + 3d₅ + 2d₆) mod 10.
S = 7d₁ + 6d₂ + 5d₃ + 4d₄ + 3d₅ + 2d₆ d₇ = S mod 10
dᵢare the IMO digits.
9×7 + 0×6 + 7×5 + 4×4 + 7×3 + 2×2 = 139 Check = 9 IMO number = IMO 9074729
IMO Ship Number Calculator Conversion Table
The IMO conversion table lists sample ship and company numbers with their check digit.
| First 6 digits | Weighted sum | Check | IMO number |
|---|---|---|---|
| 907472 | 139 | 9 | IMO 9074729 |
| 937621 | 148 | 8 | IMO 9376218 |
| 981125 | 136 | 6 | IMO 9811256 |
| 923321 | 110 | 0 | IMO 9233210 |
| 540045 | 81 | 1 | IMO 5400451 |
| 100000 | 7 | 7 | IMO 1000007 |
What is IMO Ship Number Calculator?
An IMO Ship Number Calculator is a tool that computes the 7th digit of an IMO ship identification number. The number stays with a ship for its whole life, through changes of name, flag, or owner.
S&P Global Maritime (formerly IHS Maritime) assigns IMO numbers for the International Maritime Organization. The same check digit rule applies to IMO company and registered owner numbers.
What are the uses of IMO Ship Number Calculator?
There are 3 main uses of the IMO Ship Number Calculator, including port clearance, vessel databases, and sanctions screening.
- Port clearance: Port authorities validate IMO numbers on arrival notices.
- Vessel databases: AIS and fleet platforms clean IMO fields.
- Sanctions screening: Compliance teams match vessels by IMO number.