Container check digit — validate an ISO 6346 number
A container number is 4 letters + 6 digits + 1 check digit (e.g. MSCU 123456 7). Letters map to values (A=10 … Z=38, skipping multiples of 11), every position is weighted 2^n, the sum modulo 11 gives the check digit (10 → 0). Type a number and see the computation.
Try it — live validator
Runs the same algorithm TrackJet’s detector uses, locally in your browser. Zero network calls.
The rule
Σ(value × 2^position) mod 11, positions 0–9; a result of 10 is written as 0. The fourth letter is the category: U (container), J (equipment), Z (chassis).