Check a container number

An ISO 6346 number is 4 letters, 6 digits and a check digit. The last digit is calculated from the first ten characters, which catches most typing mistakes before a box enters the registry. Everything here runs in your browser.

Container number

Try:

Valid: ZVMU 116022 6

Calculated check digit 6; the number ends in 6.

Check digit calculation
Character	Z	V	M	U	1	1	6	0	2	2
Value	38	34	24	32	1	1	6	0	2	2
Weight (2^n)	1	2	4	8	16	32	64	128	256	512
Product	38	68	96	256	16	32	384	0	512	1024

Sum 2426; 2426 mod 11 = 6; the check digit is that remainder mod 10 = 6. Letters count as 10 upwards and skip multiples of 11.

A matching check digit only means the number is well-formed. It does not prove the box exists or who owns it.