GDTI validator
How the GDTI format works
- Format
- 13-digit core ending in a GS1 mod-10 check digit
- Example
- 1234567890128
Things to watch for
- The fixed-length 13-digit core (a GS1 company prefix and document type) carries the mod-10 check digit checked here — a GDTI can also carry an optional variable-length document serial number appended after the core, but that serial is NOT part of the check-digit calculation and isn't validated by this tool
- Identifies a class or type of document (e.g. a bill of lading template or certificate type), not one specific physical/digital document instance — that's what the optional serial is for
- Format and checksum only — it can't confirm the document type is actually registered with a GS1 member company
^[0-9]{13}$A GDTI (Global Document Type Identifier) is the GS1 code for identifying a class of document — a tax-form template, a category of licence, a shipping document format like a bill of lading, a certificate template — rather than a product or a physical asset. Government agencies, logistics providers, and certification bodies use it so a document type stays traceable through a supply chain or a regulatory process the same way a product would be, letting a scanning or filing system confirm it’s handling the right kind of paperwork before it’s processed further.
Structure and check digit
A GDTI’s fixed-length 13-digit core carries a GS1 company prefix and a document-type reference, ending in a check digit computed over the 13 digits with the standard GS1 mod-10 rule. A GDTI can also carry an optional variable-length document serial number appended after that core, which is what turns a document type into one specific document instance — but that serial isn’t part of the check-digit calculation and isn’t validated here; only the 13-digit core is.
What validation covers here
This check confirms the core is 13 digits and that the final digit is arithmetically correct for the rest, catching a transposed digit before it’s filed into a records or compliance system. It doesn’t confirm the document type is actually registered with a GS1 member organization, or that any serialized document built on it is genuine.
Content last reviewed 2026-08-09.
GDTI FAQ
What kind of 'document' does a GDTI actually identify?
Not a physical piece of paper by itself, but a document type: a specific tax-form template, a licence category, a bill-of-lading format a shipper uses, a certificate template an issuing body defines. Pair that type with the optional serial number a GDTI can carry, and you get one specific document instance — this exact licence, this exact filed form — rather than just the class it belongs to.
Is a GDTI's check digit calculated any differently from a GTIN's?
No — it's the same GS1 mod-10 formula used across every GTIN length, applied to the 13-digit core: starting from the check digit and moving left, digits are weighted alternately by 1 and 3, and the total has to land on a multiple of ten. What differs between a GDTI and a product GTIN is what the code identifies, not the arithmetic that protects it.
Does this check confirm a document is genuine or currently valid?
No. It confirms the 13-digit core is correctly formed and its check digit is arithmetically consistent — nothing about whether the document type is registered with GS1, whether a specific serialized document is real, or whether it's still in force. That verification has to come from the issuing organization, not a format check.