Free tool
Container number check digit
Paste one or more container numbers. Each is checked against the ISO 6346 check digit — the fastest way to catch a typo before the manifest and your entry disagree.
- MSKU 704918-4Valid
- NWLU 704981-1The check digit should be 2, not 1.
- TGHU812345Check digit is 7 → TGHU8123457
How the check digit works
A container number has an owner code of three letters, a category letter (U for freight containers), six serial digits and one check digit. Each of the first ten characters gets a value (letters A=10 to Z=38, skipping multiples of 11), multiplied by 2 to the power of its position. The sum modulo 11 is the check digit, with 10 written as 0. Swapped or mistyped digits almost always break it.
Check the whole shipment, not one number
FreightProof reads the invoice, packing list and bill of lading together, validates every HTS number and container, builds the MIDs and flags what does not match — in about two minutes.