UDI decoder & check digit tool
Paste any GS1 UDI, from a label or a barcode scanner. See every field decoded, dates in plain words, and the GTIN check digit verified.
🔒 Runs in your browser. Nothing you paste is sent anywhere.
What it checks
Accepts label text with brackets, raw scanner data with FNC1/GS separators (ASCII 29, <GS> or |), ]d2 / ]C1 prefixes, and GS1 Digital Link URLs.
How a GS1 UDI is built
A UDI has two parts: the device identifier, which never changes for a model, and the production identifiers, which change per lot or unit.
The device identifier
The GTIN in AI (01). It identifies the model and packaging level, and it is the key you register in GUDID and EUDAMED. Its last digit is a check digit that catches typing errors.
The production identifiers
Lot (10), serial (21), expiry (17) and manufacture date (11). If one of these is printed on the label, it must also be in the barcode.
Separators
Fixed-length fields such as (01) and (17) need no separator. A variable field such as a lot number needs a GS separator when more data follows it, or the scanner cannot tell where it ends.
Common UDI Application Identifiers
| AI | Meaning | Format |
|---|---|---|
| (01) | GTIN (the UDI-DI) | 14 digits, fixed |
| (10) | Batch / lot | up to 20, variable |
| (11) | Manufacture date | YYMMDD |
| (17) | Expiry date | YYMMDD |
| (21) | Serial number | up to 20, variable |
| (240) | Additional product ID | up to 30, variable |
| (30 / 37) | Count of items | up to 8, variable |
| (422) | Country of origin | 3 digits |
| (7240) | Protocol ID | up to 20, variable |
| (8020) | Payment slip reference | up to 25, variable |
Reading YYMMDD dates
GS1 dates are six digits: year, month, day. 271231 is December 31, 2027. A day of 00 means the last day of the month, so 280200 is February 29, 2028.
Need your UDIs checked at scale?
We audit GTIN allocation, label data and GUDID / EUDAMED records across your whole catalogue. Book a free 15–30 minute call to see how.
Book a Free Video ConsultationNo obligation. You get a list of the gaps we find, recommended next steps and a clear scope if you want our help.
