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UDI Overview & Two-Component Structure

US-unique

While UDI has become an international standard (via IMDRF), the US FDA UDI system under 21 CFR Part 830 was one of the first and most comprehensive implementations globally.

What is UDI?​

The Unique Device Identification (UDI) system requires device labels to bear a unique identifier that allows traceability through the distribution chain and supports post-market safety activities. Regulated under 21 CFR Part 830 and FD&C Act § 519(f).

Two-component UDI structure​

Each UDI consists of two components:

1. Device Identifier (DI)​

  • Identifies the specific version or model of the device
  • Remains constant for all units of the same version/model
  • Issued by an FDA-accredited issuing agency (GS1, HIBCC, or ICCBBA)
  • Must be submitted to the GUDID database

2. Production Identifier (PI)​

  • Contains variable production information — one or more of:
    • Lot or batch number
    • Serial number
    • Manufacturing date
    • Expiration/use-by date
  • Changes with each production unit (for serialised devices) or production lot

UDI on the label​

The UDI must appear on the device label in:

  • Human-readable format (Plain text)
  • Automatic identification and data capture (AIDC) format — typically a barcode (GS1-128, GS1 DataMatrix, or equivalent per the issuing agency)

Official resources​