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A lot number is a distinctive combination of letters, numbers or symbols from which the complete history of the manufacture, processing, packing, holding and distribution of a batch or lot can be determined. That is the wording of the US drug manufacturing rules. For medical devices, the lot or batch is one of the items (lot or batch, serial number, expiration date and manufacturing date) that FDA’s unique device identifier rules call production identifiers.
Short answer
A lot number names a group of items made under essentially the same conditions, not a single item. It lets a manufacturer, distributor or clinic tie a product in hand back to the production run it came from. A serial number, by contrast, identifies one specific device. The FDA definitions below cover drugs and medical devices.
Definition and scope
Two parts of the Code of Federal Regulations define the terms, and they are worded differently because they cover different product classes.
Drugs and other materials: 21 CFR 210.3
The current good manufacturing practice definitions treat three related terms:
- Batch: a specific quantity of a drug or other material intended to have uniform character and quality, within specified limits, produced according to a single manufacturing order during the same cycle of manufacture.
- Lot: a batch, or a specific identified portion of a batch, having uniform character and quality within specified limits. For a drug product made by a continuous process, a lot is a specific identified amount produced in a unit of time or quantity in a manner that assures uniform character and quality within specified limits.
- Lot number, control number or batch number: any distinctive combination of letters, numbers or symbols, or any combination of them, from which the complete history of the manufacture, processing, packing, holding and distribution of a batch or lot of drug product or other material can be determined.
Devices: 21 CFR 830.3
For the unique device identifier (UDI) system, lot or batch means one finished device or more that consist of a single type, model, class, size, composition or software version, manufactured under essentially the same conditions and intended to have uniform characteristics and quality within specified limits.
How a lot number is used on labels
Under 21 CFR 830.3, a UDI has a fixed part that identifies the device model and a conditional, variable production identifier. The production identifier identifies one or more of: the lot or batch within which a device was manufactured, the serial number of a specific device, the expiration date of a specific device, and the date a specific device was manufactured. For a human cell, tissue or cellular or tissue-based product (HCT/P) regulated as a device, it also covers the distinct identification code.
21 CFR 801.40 adds two requirements that matter when reading a label. The UDI must be presented in two forms: easily readable plain text and automatic identification and data capture (AIDC) technology, such as a barcode. And if the device label includes a lot number, serial number, expiration date or manufacturing date, the UDI must include a production identifier segment that conveys that information. For the label side of this, see the CASRAI guide to UDI labeling and GUDID submission.
The definitions in 21 CFR 210.3 and 830.3 describe what a lot number must make possible (tracing a history). They do not set a character pattern for the number.
Lot, batch, serial number and expiration date compared
| Term | What the regulation says | Source |
|---|---|---|
| Lot (drug) | A batch, or a specific identified portion of a batch, of uniform character and quality within specified limits | 21 CFR 210.3(b) |
| Batch (drug) | A specific quantity of material produced according to a single manufacturing order during the same cycle of manufacture | 21 CFR 210.3(b) |
| Lot or batch (device) | One or more finished devices of a single type, model, class, size, composition or software version, made under essentially the same conditions | 21 CFR 830.3 |
| Lot number | A distinctive code from which the full manufacture-to-distribution history of the lot can be determined | 21 CFR 210.3(b) |
| Serial number | A production identifier for a specific device | 21 CFR 830.3 |
| Expiration date | The date by which the label states the device must or should be used | 21 CFR 830.3 |
The practical difference follows from these definitions. A lot or batch is a group, so every unit in it can share one lot number. A serial number points to a specific device. An expiration date is a date on the label. These can appear together in a UDI production identifier, along with the manufacturing date.
Where it matters for labs and clinics
Because the lot number is the code that ties a received product to its production history, it is a field that supply records can capture at receipt. A receiving log built only from the definitions above would hold:
- the lot or batch number as printed on the label;
- the expiration date, where the label gives one;
- the serial number, where the product carries one.
Related CASRAI pages show where this surfaces in practice: biomedical equipment inventory tracking (a UDI is a device identifier plus a production identifier), the vendor onboarding documentation checklist (lot-traceability confirmation), and the Drug Supply Chain Security Act guide, where lot information is part of drug transaction records. A related term is the electronic batch record.
Common misunderstandings
“A lot number identifies one unit.”
It does not. By the 830.3 and 210.3 definitions a lot is a group made under essentially the same conditions; a serial number is what identifies a specific device.
“Lot number and batch number are different things.”
The drug rule lists them together (“lot number, control number, or batch number”) as the same kind of code. A lot is a batch or an identified portion of a batch, so the two terms overlap closely.
“The lot number tells you the expiry.”
In the UDI definitions, lot or batch and expiration date are separate production-identifier items. Read the expiration date from the label; do not infer it from the lot code.
“There is one mandated lot-number format.”
The definitions in 21 CFR 210.3 and 830.3 describe what the number must allow (tracing the history), not a character pattern.
FAQ
What is a lot number?
A distinctive code of letters, numbers or symbols from which the complete manufacture, processing, packing, holding and distribution history of a batch or lot can be determined (21 CFR 210.3).
Is a lot number the same as a serial number?
No. A lot covers one or more finished devices made under essentially the same conditions; a serial number identifies a specific device. Both are separate production-identifier items in a UDI (21 CFR 830.3).
Must a device label show a lot number?
Under 21 CFR 801.40, if the label includes a lot number, serial number, expiration date or manufacturing date, the UDI must include a production identifier segment conveying it, in plain text and AIDC form.
Sources
Checked 2026-10-29.
- 21 CFR 830.3, Definitions (UDI), eCFR: https://www.ecfr.gov/current/title-21/part-830/section-830.3, checked 2026-10-29.
- 21 CFR 210.3, Definitions (drug cGMP), eCFR: https://www.ecfr.gov/current/title-21/part-210/section-210.3, checked 2026-10-29.
- 21 CFR 801.40, Form of a unique device identifier, eCFR: https://www.ecfr.gov/current/title-21/part-801/section-801.40, checked 2026-10-29.
