The UDI (Unique Device Identification) is the unique device identifier for medical devices. Made up of a device identifier (UDI-DI) and a production identifier (UDI-PI), it is placed on the label as a barcode and human readable text and stored in the UDI database in Eudamed or in the FDA's GUDID.
Definition and structure
The UDI (Unique Device Identification) is a system for the unique identification of medical devices across their distribution and use. Under EU Regulation 2017/745 (MDR), the UDI is a series of numeric or alphanumeric characters that is created through internationally accepted device identification and coding standards and that allows the unambiguous identification of specific devices on the market (Art. 2(15)). The UDI consists of two parts:
- UDI-DI (Device Identifier): the part specific to the manufacturer and the device model. It serves as the access key to the information stored in the UDI database.
- UDI-PI (Production Identifier): the part for the production unit, such as lot number, serial number, software identification, and manufacturing or expiry date.
“Unique” does not mean here that each production unit receives its own serial number (Annex VI Part C, Section 1). In addition, the EU has the Basic UDI-DI as the primary identifier of a device model. This identifier is the main key for the records in the UDI database and appears in the EU declaration of conformity (Art. 27(6)). The US has no Basic UDI-DI. The MDCG describes it as an additional EU requirement (MDCG 2022-7).
EU UDI system under the MDR
Art. 27 MDR divides the UDI system into four elements: the production of the UDI, its placement on the label or packaging, its storage by economic operators, health institutions and healthcare professionals, and the UDI database. Before placing a device on the market, the manufacturer assigns a UDI to the device and to all higher levels of packaging. Shipping containers do not count as a higher level of packaging. The UDI is also used for reports of serious incidents and of field safety corrective actions. The list of all UDIs assigned is part of the technical documentation (see CE marking and technical documentation).
The UDI is created in accordance with the rules of an issuing entity designated by the Commission. Implementing Decision (EU) 2019/939 designated GS1 AISBL, the Health Industry Business Communications Council (HIBCC), ICCBBA and IFA GmbH (German: Informationsstelle für Arzneispezialitäten). Implementing Decision (EU) 2024/2120 extended these designations until June 27, 2029. Under Annex VI Part C, Section 2.4, only the coding standards of these entities may be used.
A new UDI-DI is required when a change could lead to misidentification or ambiguity in traceability, for example when the trade name, version or model, packaging quantity or sterility changes (Annex VI Part C, Section 3.9). The obligation to place the UDI carrier on the label applies in stages under Art. 123(3)(f) MDR: for implantable devices and Class III since May 26, 2021, for Classes IIa and IIb since May 26, 2023, and for Class I since May 26, 2025. For reusable devices with the UDI carrier on the device itself, point (g) names May 26, 2023 for implantable devices and Class III, May 26, 2025 for Classes IIa and IIb, and May 26, 2027 for Class I (as of October 2026).
UDI database and EUDAMED (as of October 2026)
The UDI database is part of the European Database on Medical Devices (EUDAMED). The Commission operates it to validate, collate and make available to the public the data elements from Annex VI Part B (Art. 28). The UDI-PI and confidential commercial information cannot be stored in it. Before placing a device on the market, the manufacturer enters the Basic UDI-DI together with the core data elements (Art. 29(1)). These include, among others, quantity per package, manufacturer, risk class, trade name, single use, sterility and the market status. A URL for additional information, such as an electronic instructions for use, is optional. If an element changes without a new UDI-DI, the record must be updated within 30 days (Annex VI Part C, Section 5.8).
With Decision (EU) 2025/2371 of November 26, 2025, the Commission confirmed that four Eudamed systems are functional, including the UDI database and the system for the registration of devices (Art. 28 and 29 MDR). The decision was published on November 27, 2025. Under Art. 123(3)(d) MDR, the obligations apply from the date six months thereafter. The Irish authority HPRA states May 28, 2026 as the start of mandatory use. For devices that continue to be placed on the market, Art. 123(3)(e) names a period of twelve months from publication, which HPRA gives as November 28, 2026. Whether a deadline applies in an individual case should be checked by the manufacturer against the decision and the Commission's communications.
UDI in the US: 21 CFR Part 830 and GUDID
In the US, the FDA regulates the UDI in 21 CFR Part 801 Subpart B (labeling) and 21 CFR Part 830 (requirements for the UDI and the database). The label and every package of a medical device must bear a UDI (§ 801.20). The obligation was introduced in stages by risk class, starting in 2014 with Class III. The UDI consists of the device identifier, which identifies the version or model and the labeler, and, where applicable, the production identifier with lot, serial number, expiration date or manufacturing date (§ 830.3).
A UDI must be issued under a system operated by the FDA or by an FDA-accredited issuing agency and must conform to the standards ISO/IEC 15459 (Parts 2, 4 and 6) (§ 830.20). The FDA lists GS1, HIBCC and ICCBBA as accredited issuing agencies (as of October 2026). The UDI must be provided in two forms, as easily readable plain text and as AIDC (automatic identification and data capture). If the AIDC technology is not evident at first glance, the label must disclose its presence (§ 801.40).
Exceptions are regulated in § 801.30, for example for investigational devices, custom devices or devices for export. Devices in the primary packaging of a combination product are also excepted under conditions. Labelers submit device data to the Global Unique Device Identification Database (GUDID). The GUDID contains only the device identifier, not the production identifier, and is publicly accessible via AccessGUDID. The mandatory data under § 830.310 include the premarket submission number, such as that of a 510(k) or a PMA, or an indication of an exemption.
EU and US compared
| Feature | EU (MDR) | US (FDA) |
|---|---|---|
| Legal basis | Art. 27 to 29, Annex VI | 21 CFR Part 801 Subpart B, Part 830 |
| Components | UDI-DI and UDI-PI, plus Basic UDI-DI | Device identifier and production identifier |
| Issuing entities | GS1 AISBL, HIBCC, ICCBBA, IFA GmbH | GS1, HIBCC, ICCBBA |
| Database | UDI database in Eudamed | GUDID |
| Form on the label | AIDC and human readable interpretation (HRI) | AIDC and easily readable plain text |
The UDI systems were aligned within the International Medical Device Regulators Forum (IMDRF) and are largely comparable. According to MDCG 2022-7, the same UDI labeling can be used in both jurisdictions in individual cases if an issuing entity active in both markets was used. If a change under the rules of one jurisdiction triggers a new UDI-DI, the label must be adapted.
UDI carrier, labeling and usability
The UDI does not replace any other labeling requirements but comes in addition (Annex VI Part C, Section 2.1). The UDI carrier, that is, the AIDC and HRI representation of the UDI, is placed on the label or on the device and on all higher levels of packaging. Some requirements directly concern legibility and findability:
- The UDI carrier must be legible in normal use throughout the expected lifetime (Section 4.11) and must be accessible for scanning during normal operation or storage (Section 4.14).
- If the label contains other AIDC carriers, the UDI carrier must be easily identifiable (Section 4.5).
- Where there is significant space constraint, the AIDC format is sufficient. For devices intended for use outside healthcare facilities, such as in home care, the human readable form must be used instead, even if this leaves no space for AIDC (Section 4.7).
- For reusable devices, the carrier must be permanent and legible after each reprocessing (Section 4.10). US law requires direct marking for devices intended to be used more than once and reprocessed before each use (§ 801.45). Anyone using an exception documents the rationale in the design files under 21 CFR 820.10(c) (see QMSR and design controls).
- For software, the UDI appears in an easily accessible window in human readable plain text, for example in the About window or start screen (Annex VI Part C, Section 6.5.4). The FDA requires plain text at startup or via a menu command (§ 801.50).
For context: Neither the MDR nor 21 CFR Part 801 and 830 prescribe that the summative evaluation test the UDI. Use-related aspects are, however, the position, identifiability and legibility of the carrier, scanning in everyday clinical practice, legibility after reprocessing, and findability in software. Whether such aspects become part of the use-related risk analysis or of an evaluation depends on the risk in the individual case. The design of the packaging also touches on the topic (see packaging usability).
The UDI is the unique device identifier for medical devices. It consists of the UDI-DI, which identifies manufacturer and device model, and the UDI-PI for the production unit. In the EU, Art. 27 to 29 and Annex VI of the MDR regulate the system, in the US 21 CFR Part 801 Subpart B and Part 830.
The UDI-DI is stored in the UDI database of Eudamed or in the FDA's GUDID. The EU additionally has the Basic UDI-DI. Issuing entities are GS1, HIBCC, ICCBBA and IFA in the EU, and GS1, HIBCC and ICCBBA in the US.
For usability, the legibility, position, identifiability and findability of the UDI carrier are relevant, for example in home use, reprocessing and software. The MDR and FDA law name no test requirements of their own for this.
Frequently asked questions (FAQ)
What is the difference between UDI-DI and UDI-PI?
The UDI-DI is a code specific to a device model and its manufacturer and serves as the access key to the information in the UDI database. The UDI-PI identifies the production unit, for example through lot number, serial number, software identification, and manufacturing or expiry date.
What is the Basic UDI-DI?
The Basic UDI-DI is the primary identifier of a device model in the EU. This identifier is the main key for the records in the UDI database and appears in the EU declaration of conformity and in certificates. The US system does not have it; the MDCG describes it as an additional EU requirement.
Who issues UDIs?
In the EU, the Commission has designated GS1 AISBL, HIBCC, ICCBBA and IFA GmbH as issuing entities, most recently extended until June 27, 2029. In the US, the FDA lists GS1, HIBCC and ICCBBA as accredited issuing agencies. Manufacturers use only the standards of one of these entities.
Does the UDI have to be registered in EUDAMED?
Yes. Before placing a device on the market, the manufacturer enters the Basic UDI-DI with the core data elements in the UDI database. The mandatory use of the Eudamed modules concerned was triggered by Decision (EU) 2025/2371 (as of October 2026). The UDI-PI is not entered in the database.
Is the UDI part of usability testing?
Neither the MDR nor FDA law explicitly requires this. Legibility, position and identifiability of the UDI carrier are, however, use-related aspects of the labeling. Whether they flow into the use-related risk analysis and an evaluation depends on the risk in the individual case.
Are you planning UDI labeling or packaging for the EU and US? We support you in integrating the legibility, position and identifiability of the UDI carrier into your usability activities.
More about our usability engineeringSources
- Regulation (EU) 2017/745 on medical devices (MDR)
- EUDAMED, European Database on Medical Devices
- 21 CFR Part 820, Quality Management System Regulation (QMSR)
- 21 CFR Part 830, Unique Device Identification
- 21 CFR Part 801 Subpart B, Labeling Requirements for Unique Device Identification
- FDA: Global Unique Device Identification Database (GUDID)
- FDA: Contact an FDA-accredited issuing agency
- FDA: UDI Compliance Policies and UDI Rule Compliance Dates
- MDCG 2022-7, Questions and Answers on the Unique Device Identification system (May 2022)
- Commission Implementing Decision (EU) 2019/939 designating issuing entities for the assignment of UDIs
- Commission Implementing Decision (EU) 2024/2120 extending the designation of UDI issuing entities
- Commission Decision (EU) 2025/2371 on the functionality of certain Eudamed systems
- HPRA: Mandatory use of EUDAMED modules for medical devices