Articles Technical Documentation

Updated December 2, 2022

How to Get a UDI (Unique Device Identifier) For MDR Compliance

Sören Hornof

When to get your UDI?

The UDI (Unique Device Identification) is mandatory for medical devices according to the MDR as of now. However, there are different grace periods depending on the classification:

  • MD Class III: May 26, 2021
  • MD Class II: May 26, 2023
  • MD Class I: May 26, 2025

(MDR Art. 123 para. 3f)

  • IVD Class D: May 26, 2023
  • IVD Class B & C: May 26, 2025
  • IVD Class A: May 26, 2027

(IVDR Art. 113 para. 3e)

Where to get an UDI?

You can get UDIs here:

For simplicity, we’ll just look at GS1 and how their standards translate to the UDI system.

The companies do not issue UDIs per se, but they do issue their own standardized numbers and codes, which then translate to the UDI requirements. So don’t despair when searching for the button where to buy the UDI.

By the way: It makes sense to get your UDI from GS1, especially if you’re planning to sell your device in many markets. GS1 standards are acknowledged by most of the countries (incl. USA, EU, India, China, Japan) whereas for example IFA standards are only accepted in the EU. For HIBCC and ICCBBA it would make sense to check whether those standards are accepted in your target markets.

Which UDI to get?

It would be too simple if you could just order one number for your device, wouldn’t it? So here you go:

At first, you need a Basic UDI-DI.
Then, you need the UDI-DI.
And then you need a UDI-PI, but you can come up with that by yourself.

You only need one Basic UDI-DI per device, but the UDI-DI changes with every significant update, so it makes sense to buy several of them.

The confusion is virtually pre-programmed, as the regulators were once again not particularly creative when it came to inventing the terminology. Just try to avoid mixing up Basic UDI-DI and UDI-DI.

How to get my UDI from GS1?

If you’ve decided to go with GS1, at first, you need to order GS1 Complete. Then, within 2 working days, you’ll get access do your GCP (GS1 Company Prefix) and your GLN (Global Location Number). You need them later to generate your UDIs.


From GS1, you can use the GMN <(Global Model Number) as Basic UDI-DI.

Generating the GMN (Basic UDI-DI):

  • Go to the GS1 GMN Generator.
  • Take your GCP (GS1 Company Prefix), which is the “Basic number” in your GS1 Dashboard.
  • Provide an arbitrary name for your product class as “Internal number, or model reference”. Watch out: It’s case-sensitive.
  • Hit “Calculate”.

GMN Calculator

The calculation that has been done is reflected in the “check pair”, which is the red “X8” in our example. You can enter the X8 in the text box above and “validate” it. I’m not sure why you’d ever want to do that.


A new UDI-DI is required whenever there is a change that could lead to misidentification of the device and/or ambiguity in its traceability; in particular, any change of one of the following UDI database data elements shall require a new UDI-DI:

  • (a) name or trade name,
  • (b) device version or model,
  • (c) labelled as single use,
  • (d) packaged sterile,
  • (e) need for sterilization before use,
  • (f) quantity of devices provided in a package,
  • (g) critical warnings or contra-indications: e.g. containing latex or DEHP.

A new UDI-DI shall be required whenever there is a modification that changes:

  • (a) the original performance;
  • (b) the safety or the intended use of the software;
  • (c) interpretation of data.
  • Such modifications include new or modified algorithms, database structures, operating platform, architecture or new user interfaces or new channels for interoperability.

The UDI-DI therefore changes for significant modifications to the device.

In GS1 this number is the GTIN (Global Trade Item Number). It should appear in EUDAMED and on the product label.

The GTIN is composed of the GLN (Global Location Number), a numbering of the product variant and a check digit, which is automatically calculated. You can set a GLN in the GLN Manager.

To set a new GTIN (UDI-DI), navigate to the GTIN Manager.

There, you can enter the details of your new product variant:

GTIN Calculator


For the UDI-PI you can use the GS1 Application Identifier (AI). It does not have to be generated. Instead, you just use the gs1-predefined-identifiers.

  • Expiration date AI(17) - e.g. 141120
  • Batch - lot AI(10) - e.g. 1234AB
  • Serial number AI(21) - e.g. 12345XYZ
  • Manufacture date AI(11) - e.g. 250717

Combined, the UDI-PI would look like this:


The UDI-PI represents the device’s serial number, lot number, software identification, and date of manufacture or expiration, or both.

You are free to choose which information to provide in the UDI-PI. For software it makes sense to use the software version number. This is usually sufficient information. You may not want to include the third digit patch number and change your labeling design for every patch release, but again: this is up to you.

The MDR recommends: If there is only a manufacturing date on the label, this shall be used as the UDI-PI, which makes perfect sense in case of bug fixes etc.

Minor software revisions are generally associated with bug fixes, usability enhancements that are not for safety purposes, security patches or operating efficiency.

Minor software revisions shall be identified by a manufacturer-specific form of identification.

The UDI (combined UDI-DI + UDI-PI) of the device should:

  • appear on the labels or on the device itself, as applicable, and all higher levels14 of packaging,
  • be referenced in the technical documentation.

Automatic identification and data capture (“AIDC”)

AIDC is a technology used to automatically capture data. AIDC technologies include bar codes, smart cards, biometrics and RFID. There is a requirement to also provide machine-readable labels in the MDR. However, this does not apply to standalone software products:

MDR Annex VI part C, 6.5.4 (d) only the human readable portion of the UDI shall be required in electronic displays of the software. The marking of UDI using AIDC shall not be required in the electronic displays, such as ‘about’ menu, splash screen etc.;

Why all this?

The UDI is intended to serve several purposes: Products should be easier to identify, traceability should be given, especially with regard to post-market surveillance data, and illegally marketed products should be easier to detect. The fact that a number is useful in the assignment to incident reports and that a grouping of medical devices makes sense is immediately obvious. However, why we need a Basic UDI-DI and a UDI-DI remains a big mystery, especially for software products. Also, the validity of the numbers is not necessarily immediately understandable. With the corresponding publicly available calculators, one can calculate one’s Basic UDI-DI oneself. Validation would only make sense if you could not perform the calculation yourself beforehand. In addition, medical devices are still grouped according to UMDN or EMDN. This could also have been made a bit simpler (getting rid of yet another grouping/classification system).

Helpful Resources

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Sören Hornof

Hi! I am a Pharmacist with great enthusiasm for technology and innovation. Health has always been my major passion and I strongly believe that medical devices will change the world of care. Therefore, I am very happy to be able to work with progressive startups and contribute to this development.

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