--- title: "What Is a UDI (Unique Device Identifier)?" url: https://www.uncap.com/glossary/udi author: "Denis Dyli" published: 2026-10-18 updated: 2026-10-18 summary: "A UDI (unique device identifier) is the code FDA requires on the label and package of medical devices, defined as \"an identifier that adequately identifies a device through its distribution and use.\" It joins a fixed device identifier (DI), naming the labeler and model, with a variable production identifier (PI) such as the lot, serial number or expiration date." --- # What Is a UDI (Unique Device Identifier)? > A UDI (unique device identifier) is the code FDA requires on the label and package of medical devices, defined as "an identifier that adequately identifies a device through its distribution and use." It joins a fixed device identifier (DI), naming the labeler and model, with a variable production identifier (PI) such as the lot, serial number or expiration date. **UDI (unique device identifier)**: A UDI (unique device identifier) is the code FDA requires on the label and package of medical devices, defined as "an identifier that adequately identifies a device through its distribution and use." It joins a fixed device identifier (DI), naming the labeler and model, with a variable production identifier (PI) such as the lot, serial number or expiration date. ## How it works The rule sits in 21 CFR 801.20: "The label of every medical device shall bear a unique device identifier (UDI)," and "Every device package shall bear a UDI," with exceptions the regulation lists. FDA says the UDI Rule requires device labelers to put the UDI on labels and packages and to submit device information to the Global Unique Device Identification Database (GUDID). The labeler must show the UDI in two forms: easily readable plain text, and a machine-readable form that uses automatic identification and data capture (AIDC): technology that conveys the UDI in a form that can be entered into an electronic patient record or other computer system via an automated process. Dates on labels and packages use the YYYY-MM-DD format. To develop a UDI, a labeler contacts one of the issuing agencies FDA accredits. FDA lists three: GS1, the Health Industry Business Communications Council (HIBCC) and ICCBBA. **How a UDI gets from the labeler to the database** ### 1. Issuing agency, Assigns the system An FDA-accredited issuing agency operates the system the labeler uses to issue its UDIs. ### 2. Labeler, Labels the device The labeler puts the UDI on labels and packages, in plain text and in AIDC form. ### 3. GUDID, Records the DI The labeler submits device information to GUDID, which holds only the device identifier, not the production identifier. ### 4. AccessGUDID, Open to search Anyone, including hospitals and industry, can search by device name, company or device identifier. ## What it contains Under 21 CFR 830.3, a UDI has two parts: - Device identifier (DI): "a mandatory, fixed portion of a UDI that identifies the specific version or model of a device and the labeler of that device." - Production identifier (PI): a conditional, variable portion that identifies, when it is on the label, the lot or batch, the serial number, the expiration date or the manufacture date. FDA adds a distinct identification code for certain human cell and tissue products regulated as devices. In GS1's system, the DI is a GTIN (Global Trade Item Number), and GS1 sums it up as "GTIN or GTIN + AI(s) = UDI." ## Labeler or distributor? The duty to label falls on the labeler. FDA says that in most instances the labeler is the device manufacturer, but it may also be a specification developer, a single-use device reprocessor, a convenience kit assembler, a repackager or a relabeler. A distributor that only adds its own name and contact information, without other changes to the label, has not modified the label for the purpose of deciding who the labeler is. A repackager or relabeler, by contrast, can be the labeler. This page summarizes FDA's rule; it is not legal advice. ## Example A distributor receives 100 boxes of one catheter model. Every box carries the same DI, because the DI is fixed for that model and labeler. The PI differs by lot: 40 boxes are lot A123, expiring 2027-12-31, and 60 boxes are lot A140, expiring 2028-03-31. A hospital orders 50 boxes, and the distributor ships the earlier expiry first: 40 boxes of A123 plus 10 boxes of A140. One product line on the order becomes 2 lots and 2 expiration dates, so the DI alone cannot say what was shipped. ## On Shopify Shopify lets you add up to 20 barcodes to a product or variant, and a barcode can be provided by a global registry, such as a GTIN. Its GTIN barcode type accepts 8, 12, 13 or 14 digits. As a general practice, a DI issued as a GS1 GTIN can be stored as the barcode of the variant it identifies. The production identifier is the conditional, variable portion of the UDI. Metafields let you save specialized information that isn't usually captured on product pages; Shopify's own example is a grocery store displaying a product expiration date. As a general practice, lot and expiry data comes from the system that receives and picks the stock, through an integration or a custom build. ## How Uncap helps Uncap's [medical supply page](/industry/medical-supply) is plain that lot numbers, expiry dates, UDI data and par levels belong in the system that owns receiving, allocation and fulfillment. Uncap Connect surfaces that data instead: read from the ERP, shown where a buyer or a service rep needs it, and carried onto the order record. ## Related terms - GTIN (Global Trade Item Number) - Lot number - UPC (Universal Product Code) - GS1-128 label - Item master - PIM (product information management) ## Sources - FDA: UDI Basics - 21 CFR 830.3, Definitions (Cornell LII) - 21 CFR 801.20, Label to bear a unique device identifier (Cornell LII) ## Frequently asked questions ### What does UDI stand for? Unique device identifier. FDA's program is the Unique Device Identification System, set out in the UDI Rule. ### How to get a UDI number? A device labeler contacts one of the FDA-accredited issuing agencies (GS1, HIBCC or ICCBBA) and develops the UDI in that agency's system, then submits device information to GUDID. ### Can you provide an example of a UDI? A UDI pairs a fixed device identifier for the model, such as a GS1 GTIN, with production data like lot A123 and an expiration date of 2027-12-31, shown in plain text and in machine-readable AIDC form.