ITF Generator
Interleaved 2-of-5 for even-length digit strings on corrugated cartons and warehouse labels.
How ITF is structured
Interleaved 2 of 5 prints digits in pairs: the digit in each odd position is drawn in the bars and the digit in the following even position is drawn in the spaces, so two digits occupy one five-element pattern. That interleaving is why the payload must contain an even number of digits — an odd count needs a leading zero added first. There are no separate start and stop characters beyond a narrow bar pattern at each end.
ITF check digit
No check digit is mandatory. Where one is used it is a mod-10 check digit appended to the data — same arithmetic family as the GS1 check digit — and the payload still has to stay even in length after appending, which is why an odd-length number gets a leading zero as well.
ITF compared with ITF-14
ITF-14 is the GS1-specific use of the same symbology: 14 digits, mandatory bearer bar, case-level GTIN. Code 128 C encodes digit pairs too and keeps a smaller module structure, so it is the better fit on a small label, while ITF tolerates the rough surface and ink spread of corrugated board better. Compare the ITF-14 generator page for the same breakdown of structure, check digit and use cases.
Common ITF problems
An odd number of digits was entered
Interleaving needs a partner for every digit. Add a leading zero to make the count even, and check that the leading zero is acceptable to the application that will read the returned string.
The symbol will not scan off the carton
On corrugated board, ink spread bridges the narrow bars. Print ITF with the wide-to-narrow ratio the substrate needs and add a bearer bar that frames the symbol top and bottom, which is what stops the reader from latching onto a partial row.
The scanned value has extra or missing digits
Because digits alternate between bars and spaces, a reader that locks onto the pattern one element late returns a shifted digit string. Check the quiet zones first — this symptom is almost always a narrow margin rather than a data problem.
Where ITF is used
- Outer carton and case labels printed directly on corrugated board
- Warehouse tote and pallet identification with numeric keys
- Interim carton labels before a GTIN-14 ITF-14 is assigned
Not sure this is the right symbology? The barcode format guide groups every supported 1D and 2D format by industry with its character set and limits.