What is a Serial Number in GS1?
The Serial Number (AI 21) in the GS1 system uniquely identifies an individual item within a batch or production run. This is commonly used in electronics, pharmaceuticals, medical devices, and luxury goods for tracking and authentication.
| Application Identifier (AI) | 21 |
| Data Content | Up to 20 alphanumeric characters |
| Length | Variable length |
Example of a Serial Number in a GS1 Barcode
| AI Format | (21)SN987654321 |
| Full GS1 Barcode Example (GS1-128 or GS1 DataMatrix) | 0101234567890128 21SN987654321 |
(01) = GTIN (Global Trade Item Number), (21) = Serial Number
Real-World Examples in Different Industries
Electronics (Smartphone)
| GTIN | 01234567890128 |
| Serial Number (AI 21) | SNX12345A |
| Barcode Data | (01)01234567890128(21)SNX12345A |
Meaning: A unique smartphone with serial SNX12345A.
Pharmaceutical Industry (Vaccine Dose)
| GTIN | 03456789012345 |
| Serial Number (AI 21) | VAX202400018 |
| Barcode Data | (01)03456789012345(21)VAX202400018 |
Meaning: This is an individual vaccine dose #18 from the production batch.
Medical Devices (Pacemaker)
| GTIN | 05012345678901 |
| Serial Number (AI 21) | PM4567891234 |
| Barcode Data | (01)05012345678901(21)PM4567891234 |
Meaning: This pacemaker has a unique serial number for traceability.
Luxury Goods (High-End Watch)
| GTIN | 07098765432109 |
| Serial Number (AI 21) | LUX2023X001 |
| Barcode Data | (01)07098765432109(21)LUX2023X001 |
Meaning: A unique, trackable watch produced in 2023.
Key Features of GS1 Serial Numbers
✅ Uniquely identifies a single item (not just a batch)
✅ Alphanumeric, up to 20 characters
✅ Always preceded by AI (21) in GS1 barcodes
✅ Essential for anti-counterfeiting and individual product traceability