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General regulatory information for lab, clinic and supply staff. It is not medical advice and does not replace the device labeler’s instructions or your own compliance procedures.
Short answer: what is a UDI label?
A UDI label is the label (or package label) on a medical device that carries its Unique Device Identifier, a numeric or alphanumeric code, in two forms: easily readable plain text and automatic identification and data capture (AIDC) technology such as a barcode. The code always has a device identifier segment and, when the label shows production details such as lot or expiry date, a production identifier segment (21 CFR 801.40; FDA UDI Basics, checked 2026-11-01).
Definition and scope
FDA describes a UDI as a unique code that generally has a device identifier (DI) and, when applicable, a production identifier (PI). The DI is the required, fixed part that identifies the labeler and the device version or model. The PI is conditional and variable. This page is about the label as a physical object you can inspect. For the anatomy of the two segments, see our guide to the UDI production identifier and how it differs from the DI.
A labeler is the party that applies the label, and the labeler is the one responsible for putting a UDI on device labels and packages unless an exception or alternative applies. A receiver, buyer or lab does not create the UDI; it can only check what is on the label in front of it.
What a UDI label must show: plain text and AIDC
Under 21 CFR 801.40, every UDI must meet the technical requirements of 21 CFR 830.20 and must be presented in two forms:
- Easily readable plain text, so a person can read the identifier without a scanner.
- AIDC technology, so a scanner can capture it.
If the AIDC form is not visible on inspection, the label or device package must disclose that AIDC technology is present (21 CFR 801.40(c)). In other words, a label may legitimately carry a statement about the presence of AIDC where the carrier is not obvious.
Device identifier vs production identifier on the label
The UDI must include a device identifier segment. When the label includes certain production details, the UDI must also include a production identifier segment that conveys that information (21 CFR 801.40(b)). FDA lists the production details a PI can encode: lot or batch number, serial number, expiration date, manufacturing date, and a distinct identification code for certain human cells, tissues and cellular and tissue-based products regulated as devices.
Practical consequence: a DI-only UDI is not automatically a defect. If a label shows no lot, serial, expiry or manufacture date, a PI would not be expected. If it does show one of those, it should be reflected in the UDI. FDA states that dates on the label use the standard YYYY-MM-DD format. For reading the lot itself, see how to read a lot number.
Labels, packages and direct marking
The labeler includes the UDI on device labels and packages. A reusable device that is reprocessed before each use must also carry its UDI marked directly on the device (FDA UDI Basics). So a printed label and a direct part marking are different things: the first is on the label or package, the second is on the device itself and applies to this reprocessed, reusable category. Other label content, such as symbols and directions, is covered in medical device labeling symbols and instructions for use.
The Class I UPC exception
For a Class I device that has a Universal Product Code (UPC) on its label and packages, the UPC serves as the UDI (21 CFR 801.40(d)). A plain UPC on such a label is therefore not a missing UDI. The relationship between the identifiers is explained in GTIN vs UPC.
Checklist: reading a UDI label on receipt
This checklist applies the sourced requirements above to a label you are holding. It is a reading aid, not a regulatory test.
| Check | What the rule or FDA page says |
|---|---|
| Plain-text UDI is present | Every UDI is presented as easily readable plain text (21 CFR 801.40(a)). |
| An AIDC form exists | The UDI must also be in AIDC form; if the carrier is not visible, the label or package must disclose its presence (801.40(a), (c)). |
| A DI segment is there | The UDI must include a device identifier segment (801.40(b)). |
| PI matches the production details shown | If the label shows lot, serial, expiry or manufacture date, the UDI must include a PI segment conveying it (801.40(b)). |
| Dates read YYYY-MM-DD | FDA UDI Basics: dates use the standard YYYY-MM-DD format. |
| Class I with a UPC | The UPC can serve as the UDI (801.40(d)). |
| Look up the DI, then read lot and expiry from the label | Labelers submit device data to GUDID, which contains the DI but does not include the PI (FDA UDI Basics). |
The last row is the practical gap in most explainers: the public database tells you about the device model, but the lot, serial and expiry exist only on the label. For how this connects to traceability, see medical device tracking requirements.
Common misunderstandings
“The GUDID entry is the label.”
No. GUDID is the database labelers submit to. It holds the DI and device attributes but not the PI, so it cannot replace reading the label.
“A UDI is just a barcode.”
No. The rule requires both plain text and AIDC forms, so a barcode alone does not satisfy it.
“Every UDI must contain a lot and an expiry date.”
No. The PI is conditional. It is required only when the label includes those production details.
“Direct marking is the same as the label.”
No. Direct marking on the device is a separate requirement for reusable devices that are reprocessed before each use.
FAQ
What is a UDI label?
It is a medical device label or package label that carries the device’s Unique Device Identifier in plain text and in AIDC form, with a device identifier segment and, where the label shows production details, a production identifier segment.
What are UDI label requirements?
The form requirements are in 21 CFR 801.40: technical requirements per 21 CFR 830.20, plain text plus AIDC, a DI segment, a PI segment when production details appear, a disclosure of AIDC presence when the carrier is not visible, and the Class I UPC provision.
Who applies a UDI label?
The device labeler. FDA’s rule places the obligation on the labeler, with GUDID submission also made by the labeler.
Does a UDI label include the lot number and expiry date?
Only when the label includes those details; then the PI segment conveys them, with dates in YYYY-MM-DD.
Sources
Checked 2026-11-01.
- eCFR, 21 CFR 801.40, Form of a unique device identifier: https://www.ecfr.gov/current/title-21/part-801/section-801.40 (text confirmed against https://www.law.cornell.edu/cfr/text/21/801.40)
- FDA, UDI Basics: https://www.fda.gov/medical-devices/unique-device-identification-system-udi-system/udi-basics
