GS1 Format and Application Identifiers Guide
Comprehensive guide to GS1 Application Identifiers (AIs) for barcode encoding
What is GS1? GS1 is a global standards organization that develops and maintains supply chain standards, including barcodes, for tracking products, shipments, and assets worldwide.
📋 Introduction to GS1 Application Identifiers
Application Identifiers (AIs) are standardized prefixes that define the meaning and format of data elements in GS1 barcodes. They enable structured encoding of multiple data fields within a single barcode.
Key Characteristics
- Prefix Structure: 2-4 digit numerical prefixes that identify data type
- Data Format: Each AI defines specific format rules for the following data
- Separator Function: FNC1 characters separate variable-length fields
- Global Standard: Recognized worldwide for supply chain tracking
GS1 Data Structure
Basic Format:
[AI][Data][FNC1][AI][Data][FNC1]...
Components:
- Application Identifier (AI): 2-4 digit prefix
- Data Field: Actual data in specified format
- FNC1: Field separator for variable-length fields
Example Breakdown:
Raw Data:
01123456789012315190521103210Ab1234
01 GTIN: 12345678901231
15 Best Before: 190521
10 Batch: 3210Ab1234
15 Best Before: 190521
10 Batch: 3210Ab1234
Common Application Identifiers
| AI | Description | Format | Length | Example |
|---|---|---|---|---|
| 00 | Serial Shipping Container Code (SSCC) | Numeric | 18 digits (fixed) | 001234567890123456 |
| 01 | Global Trade Item Number (GTIN) | Numeric | 14 digits (fixed) | 12345678901231 |
| 10 | Batch or Lot Number | Alphanumeric | 1-20 chars (variable) | ABC123 |
| 11 | Production Date | YYMMDD | 6 digits (fixed) | 241010 |
| 15 | Best Before Date | YYMMDD | 6 digits (fixed) | 251210 |
| 17 | Expiration Date | YYMMDD | 6 digits (fixed) | 251215 |
| 21 | Serial Number | Alphanumeric | 1-20 chars (variable) | SN123456 |
| 240 | Additional Product Identification | Alphanumeric | 1-30 chars (variable) | PRODUCT-VARIANT-A |
| 310n | Net Weight (kg) | Numeric (n=decimal places) | 6 digits (fixed) | 3101001250 (12.50 kg) |
| 37 | Number of Units Contained | Numeric | 1-8 digits (variable) | 24 |
Measurement Application Identifiers (3xxx Series)
The 3xxx series AIs are used for various measurements. The last digit (n) indicates the number of decimal places.
Weight Measurements:
- 310n: Net weight (kg)
- 311n: Length/width/height (meters)
- 312n: Width (meters)
- 313n: Depth/thickness (meters)
- 314n: Area (square meters)
- 315n: Net volume (liters)
Imperial Measurements:
- 320n: Net weight (pounds)
- 321n: Length/width/height (inches)
- 322n: Width (inches)
- 323n: Depth/thickness (inches)
- 324n: Area (square inches)
- 325n: Net volume (quarts)
Decimal Place Examples:
3101001250 = 12.50 kg (1 decimal place)3102001250 = 1.250 kg (2 decimal places)3103001250 = 0.1250 kg (3 decimal places)
Practical Examples
Example 1: Food Product
Encoded Data:
01123456789012315251210103210ABC
01 GTIN: 12345678901231
15 Best Before: December 10, 2025
10 Batch: 3210ABC
15 Best Before: December 10, 2025
10 Batch: 3210ABC
Example 2: Shipping Container
Encoded Data:
0098765432109876543111241010
00 SSCC: 98765432109876543
11 Production Date: October 10, 2024
11 Production Date: October 10, 2024
Example 3: Complex Product with Measurements
Encoded Data:
0112345678901231152512101021SN78910031010012503720024
01 GTIN: 12345678901231
15 Best Before: December 10, 2025
21 Serial Number: SN78910
15 Best Before: December 10, 2025
21 Serial Number: SN78910
3101 Net Weight: 12.50 kg
37 Units Contained: 24 pieces
37 Units Contained: 24 pieces
Technical Implementation Guidelines
Encoding Rules:
- Do not encode bracket symbols [] in actual barcode
- Use FNC1 (Function Code 1) as field separator
- FNC1 represented as
\Fin some systems - Terminate variable-length fields with FNC1
- Omit FNC1 after the last data field
- Check digit validation for GTIN and SSCC
Validation Tips:
- Verify AI format against official GS1 specifications
- Validate data length constraints
- Check date format (YYMMDD) validity
- Ensure alphanumeric fields use allowed characters
- Implement check digit algorithms for numeric IDs
- Test barcode readability across different scanners
Compatible Barcode Types
Linear Barcodes:
- GS1-128: Most common for GS1 data
- GS1 DataBar: Compact linear format
- ITF-14: For GTIN-14 only
2D Barcodes:
- GS1 Data Matrix: High density 2D
- GS1 QR Code: Quick Response format
- GS1 Composite: Combined linear + 2D
Use Cases:
- Retail: GTIN + price/weight
- Healthcare: Lot numbers + expiry
- Logistics: SSCC + tracking info
Quick Reference
Fixed Length AIs:
00 | SSCC (18) |
01 | GTIN (14) |
11 | Production Date (6) |
15 | Best Before (6) |
17 | Expiry Date (6) |
310n-315n | Measurements (6) |
Variable Length AIs:
10 | Batch/Lot (1-20) |
21 | Serial Number (1-20) |
240 | Additional ID (1-30) |
37 | Count (1-8) |
90-99 | Company Internal (1-30) |