UDI Barcode Guide: FDA Unique Device Identification
Every medical device sold in the US needs a Unique Device Identifier. Here's what a UDI actually contains, which barcodes carry it, and how it's different from a drug's NDC.
What Is a UDI?
UDI (Unique Device Identification) is the FDA's system for identifying medical devices, requiring most devices to carry a unique identifier on their label in both human-readable text and a machine-readable barcode. A UDI is made of two distinct parts:
- Device Identifier (DI): A fixed, mandatory code that identifies the labeler and the specific device version or model — it never changes for that model.
- Production Identifier (PI): One or more variable pieces of data specific to the unit or batch — typically a lot or batch number, serial number, manufacture date, and/or expiration date.
Together, DI and PI let a hospital or distributor scan one barcode and know exactly which device, from which batch, with which expiration date, they're handling.
UDI vs. NDC: Different Products, Different Codes
These two identifiers get confused because both are FDA systems that end up as barcodes on healthcare packaging. An NDC (National Drug Code) identifies a drug. A UDI identifies a medical device — anything from a surgical instrument to an implant to a diagnostic test kit. A hospital's supply chain routinely scans both side by side, but they follow separate regulatory tracks and separate FDA databases.
Which Barcode Carries a UDI?
The FDA's UDI rule doesn't mandate a single symbology — it requires an AIDC (Automatic Identification and Data Capture) carrier readable by standard scanning equipment. In practice, that means one of three encodings, all built on the same DI/PI data:
- GS1-128: The most common choice for cartons and larger device packaging, using GS1 Application Identifiers to structure the DI and PI. See our GS1-128 guide for the underlying symbology.
- GS1 DataMatrix: Preferred for small devices and unit-of-use packaging where a linear barcode won't fit. Covered in our GS1 DataMatrix medical guide.
- HIBC: Widely used across US hospital supply chains, issued by HIBCC instead of GS1. See our HIBC barcode guide.
Getting a Compliant DI
A DI has to be unique across the entire US medical device industry, not just within your own company — so it must come from an FDA-accredited issuing agency: GS1, HIBCC, or ICCBBA (the last mainly for blood, tissue, and organ products under ISBT 128). Once assigned, the DI record also needs to be submitted to the FDA's GUDID (Global Unique Device Identification Database) before the device ships.