Device identification · EUDAMED · GS1
UDI-DI, Basic UDI-DI, GTIN and GMN – what is the difference?
The terms are closely connected, but they are not interchangeable. UDI-DI and Basic UDI-DI belong to the European regulatory system. GTIN and GMN are the identifiers used to implement them when the manufacturer chooses GS1 as its UDI issuing entity.
See how the identifiers connect ↓EU regulatory identifiers
GS1 identifiers
Start with the system
Two regulatory identifiers, two different jobs
The UDI-DI identifies a device record. The Basic UDI-DI connects a regulatory group of devices to EUDAMED and the relevant documentation.
Specific device
UDI-DI
Identifies a particular device trade item, version, configuration or packaging level. It forms the device-identifier component of the UDI.
Appears in the UDI carrierRegulatory group
Basic UDI-DI
Groups devices sharing the required regulatory characteristics and acts as the main key in EUDAMED and regulatory documentation.
Does not appear on the labelThe UDI itself consists of the UDI-DI and the UDI-PI. The Basic UDI-DI is a separate regulatory identifier and is not part of the UDI shown on the device label.
The European Union Medical Device Regulation (MDR) and In Vitro Diagnostic Medical Device Regulation (IVDR) establish a Unique Device Identification system for devices within their scope. The system supports device identification, traceability and the submission of device data to EUDAMED.
Use of the EUDAMED UDI/Devices module became mandatory on 28 May 2026 under the applicable transitional arrangements. Manufacturers must submit the required UDI and device information for devices they place on the EU market.
01
What is a UDI-DI?
The UDI-DI is the device-identifier component of the UDI. It is specific to a manufacturer and a device and provides access to the device information recorded in the UDI database.
Different device versions, configurations and packaging levels may require different UDI-DIs. The precise allocation depends on the MDR or IVDR requirements and the rules of the selected issuing entity.
The UDI-PI contains production information where applicable, such as a lot or batch number, serial number, manufacturing date or expiry date. It is the UDI-PI, not the UDI-DI alone, that can distinguish an individual serialised unit.
02
What is a Basic UDI-DI?
The Basic UDI-DI is the primary regulatory grouping key. It connects a group of devices to its EUDAMED record and to documents such as certificates, the EU Declaration of Conformity, technical documentation and, where applicable, the summary of safety and clinical performance.
A Basic UDI-DI group is not created merely because devices belong to the same commercial family or have a similar model name. The devices must share the same intended purpose, risk class and essential design and manufacturing characteristics.
A valid regulatory group
The Basic UDI-DI is submitted to EUDAMED and used in regulatory documentation. It is not placed on the device label, its packaging or the UDI carrier.
03
How do GTIN and GMN fit into the system?
Manufacturers must obtain identifiers under the rules of an issuing entity designated by the European Commission. GS1 is one of the designated issuing entities, alongside HIBCC, ICCBBA and IFA.
When GS1 is selected, the regulatory identifiers are implemented as follows:
This relationship is specific to the GS1 system. It should not be presented as a universal equation independent of the chosen issuing entity.
04
What is a GTIN?
A Global Trade Item Number (GTIN) identifies a particular trade item that may be priced, ordered or invoiced. In the medical-device context, a GTIN used as a UDI-DI can identify a particular device version, configuration or packaging level.
A GTIN does not normally identify an individual physical unit. Where individual unit identification is required, production information such as a serial number is carried in the UDI-PI.
Illustrative GTIN-13 structure
753030353XXXC
In this example, the manufacturer assigns the item reference within the range associated with its GS1 Company Prefix and calculates the final check digit. Allocation must follow the applicable GS1 GTIN rules, and every resulting GTIN must be unique.
A GTIN identifies a trade item. A logistics unit assembled for transport or storage is normally identified with an SSCC. A case or pallet may have a GTIN only when it is also treated as a trade item.
05
What is a GMN?
The Global Model Number (GMN) is the GS1 identifier used as the Basic UDI-DI. It identifies the regulatory group rather than a trade item, packaging level or individual device.
The GMN combines the manufacturer’s GS1 Company Prefix with a company-assigned model reference. Together, those two elements may contain up to 23 characters. Two mandatory check characters are then added.
Illustrative GMN structure
753030353AAAAAW8
The available length of the model reference therefore depends on the length of the GS1 Company Prefix. It is not correct to describe the model reference itself as always having a maximum of 23 characters.
06
Key differences between GTIN and GMN
| Feature | GTIN used as UDI-DI | GMN used as Basic UDI-DI |
|---|---|---|
| Purpose | Identifies a particular device trade item or packaging level | Groups devices for regulatory purposes |
| Scope | Specific to a device version, configuration or packaging level | Covers devices sharing the required regulatory characteristics |
| Format | Numeric GTIN containing a check digit | Alphanumeric GS1 Company Prefix and model reference followed by two check characters |
| UDI carrier | Used as the device-identifier component | Does not appear on the label or packaging |
| Regulatory documentation | Identifies the relevant device record | Acts as the principal grouping key |
07
How to generate GTIN and GMN identifiers
- Use the GS1 Company Prefix assigned to your company.
- Assign an item reference under the applicable GTIN allocation rules.
- Calculate the check digit and verify that the complete GTIN is unique.
- Use the GS1 Company Prefix assigned to your company.
- Assign a model reference appropriate for the Basic UDI-DI group.
- Generate the two mandatory check characters with the GS1 tool.
GS1 provides a check-character calculator. Number generation should follow the regulatory grouping decision rather than precede it.
In practical terms
The identifiers connect different levels of the same product system
The UDI-DI identifies a particular device trade item or packaging level. The Basic UDI-DI groups devices that share the same intended purpose, risk class and essential design and manufacturing characteristics. When GS1 is used, these functions are implemented through the GTIN and GMN respectively.
Correct assignment involves more than generating valid numbers. Manufacturers must first define the device and its regulatory grouping correctly, then apply the MDR or IVDR requirements and the allocation rules of the selected issuing entity.
Official references
Need to structure your device identifiers?
Define the regulatory grouping before assigning the numbers
MDRC helps manufacturers structure device families, determine the appropriate Basic UDI-DI groups and prepare consistent device data for EUDAMED.
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