Labels and Barcoding
Barcode technology is the backbone of warehouse automation, enabling fast and accurate identification of products, locations, and containers throughout the facility. By encoding information into machine-readable formats, barcode systems eliminate manual data entry errors, accelerate processing speed, and provide the real-time visibility that modern warehouse management systems depend on. A well-designed labeling and barcoding strategy transforms a warehouse from a chaotic stockpile into a precisely orchestrated logistics engine.
According to industry studies, implementing barcode systems reduces data entry errors from approximately 1 in 300 keystrokes to just 1 in 3 million scans — a 99.9997% accuracy improvement. This precision is why barcoding has become the universal language of supply chain operations, connecting manufacturers, distributors, retailers, and carriers through standardized identification schemes.
Barcode Types in Warehousing (1D, 2D, RFID)
Warehouses use three primary categories of automatic identification technologies, each with distinct advantages for different applications.
1D Linear Barcodes
One-dimensional barcodes encode data in a series of vertical bars and spaces of varying widths. They are read by laser scanners moving horizontally across the symbol. The most common 1D formats in warehouses include:
| Barcode Type | Character Set | Max Data | Typical Use Case |
|---|---|---|---|
| Code 128 | Full ASCII (alphanumeric + symbols) | ~80 characters | General warehouse inventory, carton labels, internal tracking |
| Code 39 | Alphanumeric + 7 symbols | ~40 characters | Legacy systems, asset tracking, simple applications |
| Interleaved 2 of 5 | Numeric only | Variable | Case labels, distribution boxes (often as ITF-14) |
| UPC-A / EAN-13 | Numeric only (12-13 digits) | Fixed length | Retail product identification, consumer goods |
| GS1-128 | Full ASCII with Application Identifiers | Variable | Shipping labels, pallet labels, logistics with structured data fields |
GS1-128 (formerly UCC-128) is the workhorse of warehouse shipping labels. It uses Application Identifiers (AIs) to structure multiple data fields into a single barcode — for example, AI (01) for GTIN, AI (10) for lot number, AI (15) for expiration date, and AI (37) for quantity. This allows a single scan to capture all critical information about a shipment.
GS1-128 barcodes use standardized Application Identifier codes to structure data. For example: (01)09521101530001(17)210119(10)AB-123 encodes GTIN (01), expiration date YYMMDD (17), and lot number (10) in a single barcode. The FNC1 character separates variable-length fields.
Advantages of 1D barcodes:
- Simple, low-cost printing (thermal transfer, laser, inkjet)
- Fast scanning with inexpensive laser scanners
- Universal compatibility across all systems
- Durable — readable even when partially damaged
Limitations:
- Limited data capacity (typically under 100 characters)
- Require horizontal orientation and clean line-of-sight
- Cannot encode complex data structures efficiently
2D Matrix Barcodes
Two-dimensional barcodes encode data in both horizontal and vertical dimensions, creating a matrix or mosaic pattern. They hold significantly more information in a smaller footprint and include built-in error correction. Common 2D formats include:
| Barcode Type | Max Data | Error Correction | Typical Use Case |
|---|---|---|---|
| QR Code | ~4,296 alphanumeric characters | Up to 30% recovery | Small parts, high-density labeling, mobile scanning, GS1 Digital Link |
| Data Matrix | ~3,116 alphanumeric characters | Up to 25% recovery | Small item labeling, electronics, pharmaceuticals, traceability |
| PDF417 | ~1,850 alphanumeric characters | Reed-Solomon | Driver's licenses, identification cards, some shipping labels |
| GS1 DataMatrix | Variable (GS1-structured) | Up to 25% recovery | Healthcare (UDI), small product labeling, direct part marking |
Data Matrix is particularly valuable in warehouses handling small parts, pharmaceuticals, or high-value electronics. It can be printed as small as 2mm × 2mm and still be reliably scanned, making it ideal for component-level tracking.
QR Codes are increasingly used for mobile-first workflows — warehouse staff can use smartphones to scan QR codes that link to digital work instructions, safety data sheets, or real-time inventory dashboards.
Advantages of 2D barcodes:
- High data density — store URLs, serial numbers, expiration dates, lot codes, and more in a single symbol
- Omnidirectional scanning — readable from any angle
- Error correction — damaged codes remain scannable if enough of the pattern survives
- Smaller footprint for the same data content
Limitations:
- Require 2D imager scanners (more expensive than laser scanners)
- More complex printing requirements
- Larger file sizes for digital label design
RFID (Radio Frequency Identification)
RFID tags contain a microchip and antenna that transmit data via radio waves when energized by an RFID reader. Unlike barcodes, RFID does not require line-of-sight and can be read in bulk — a reader can scan dozens or hundreds of tags simultaneously.
| RFID Type | Read Range | Use Case | Cost per Tag |
|---|---|---|---|
| Passive UHF RFID | 1-12 meters | Pallet tracking, carton tracking, inventory visibility | $0.08 - $0.50 |
| Active RFID | Up to 100+ meters | Vehicle tracking, high-value asset monitoring, yard management | $15 - $50+ |
| NFC (Near Field Communication) | 0-10 cm | Authentication, small item tracking, mobile interaction | $0.20 - $1.00 |
Warehouses typically use passive UHF RFID for pallet-level and carton-level tracking. RFID portals (dock doors equipped with readers) automatically capture every tagged item entering or leaving the facility without manual scanning.
Advantages of RFID:
- No line-of-sight required — read through cardboard, plastic, and other materials
- Bulk reading — scan entire pallets or trailers in seconds
- Writable tags can be updated in the field
- Real-time location tracking when combined with fixed reader infrastructure
Limitations:
- Higher cost per tag compared to printed labels
- Metal and liquids can interfere with radio signals
- Requires specialized hardware and software integration
- Privacy and security considerations for data transmission
Many modern warehouses use a hybrid strategy: RFID for high-volume receiving and shipping portals combined with barcode scanning for directed tasks like picking and putaway. This balances cost, accuracy, and operational flexibility.
Barcode Technology Selection Guide
Choose the right identification technology based on your operational requirements:
Technology comparison summary:
| Use Case | Recommended Technology | Why |
|---|---|---|
| Retail consumer products | UPC-A / EAN-13 | Universal retail standard |
| General warehouse inventory | Code 128 | Simple, fast, universal |
| B2B shipping labels | GS1-128 | Structured multi-field data |
| Small parts (<2 cm²) | GS1 DataMatrix | High density, tiny footprint |
| Mobile/smartphone workflows | QR Code | No special scanner needed |
| Pharmaceutical traceability | GS1 DataMatrix | FDA/EU serialization compliance |
| Pallet/trailer portal automation | Passive UHF RFID | Bulk reading, no line-of-sight |
| High-value asset tracking | Active RFID | Long-range location tracking |
License Plate Numbers (LPNs)
A License Plate Number (LPN) is a unique identifier assigned to a physical container — a pallet, tote, carton, or any other handling unit — that allows a warehouse management system (WMS) to track the container and its contents as a single entity. The LPN is the unit of inventory control in modern warehouse operations.
Think of an LPN like a shipping container number in ocean freight: the container itself has an identifier, and the manifest lists what's inside. Similarly, an LPN is applied to a warehouse container, and the WMS database records the inventory items packed inside.
How LPNs Work
LPN-based inventory control follows a structured lifecycle from receiving through shipping:
Key stages in the LPN lifecycle:
- Generation: WMS creates unique LPN (from ASN or at receiving)
- Label printing: Thermal printer outputs barcode label
- Association: Items scanned into LPN (SKU, qty, lot, serial)
- Quality control (if required): Inspection before putaway
- Putaway: LPN directed to optimal storage location
- Storage tracking: Real-time location and status in WMS
- Picking: Full pallet pick or partial pick (LPN break)
- Packing/Consolidation: Repack or ship as-is
- Shipping: LPN dispatched, status updated to SHIPPED
- Exception handling: Quarantine, RTV, scrap, or regrade as needed
Benefits of LPN-Based Inventory Control
| Benefit | Description |
|---|---|
| Faster transactions | Scan one LPN instead of individual SKUs — receive a full pallet in seconds |
| Accuracy | Eliminates manual counting errors by treating containers as atomic units |
| Traceability | Complete chain of custody from receipt through shipment, critical for lot control |
| Mixed SKU handling | One LPN can contain multiple SKUs, simplifying consolidation and kitting |
| Dynamic slotting | WMS can direct LPNs to optimal locations based on velocity, size, and availability |
| Inventory visibility | Real-time location and status of every container in the facility |
LPN Formats and Standards
While LPN structure is not globally standardized like GTIN, most warehouses follow these conventions:
- Sequential numbering:
LPN0000001,LPN0000002, etc. - Prefix by type:
PLT12345(pallet),TOT67890(tote),CTN55555(carton) - Date-embedded:
LP20260211-00123(includes YYYYMMDD for easy audit trails) - Location-aware:
A01-R05-L02-001(encodes aisle-rack-level + sequence number)
Most LPNs are encoded in Code 128 or GS1-128 barcodes for flexibility and high-density data.
LPNs must remain unique across the warehouse's entire operational history — reusing old LPNs can corrupt inventory records. Most WMS platforms use auto-incrementing sequences or UUID-based generation to guarantee uniqueness.
Location Labels
Location labels identify every storage position in the warehouse, enabling directed putaway, accurate picking, and cycle counting. A well-designed location labeling system is the foundation of WMS-driven operations.
Location Naming Conventions
Most warehouses use a hierarchical alphanumeric system that mirrors the physical structure:
Common format: Aisle - Section/Bay - Rack/Shelf - Level/Tier - Bin/Position
Example: A12-R03-L05-B02
- A12 = Aisle 12
- R03 = Rack/Bay 3 within Aisle 12
- L05 = Level 5 (counting from ground up, or designated levels)
- B02 = Bin position 2 within that level
Alternative formats:
- Simplified:
01-15-03(Aisle 01, Section 15, Position 03) - Zone-based:
BULK-A-045(Bulk storage zone, Aisle A, position 045) - Floor locations:
FLOOR-A-12(floor position in Aisle A, spot 12)
The key principle: location labels should be human-readable and logically ordered so operators can visually navigate without constant WMS guidance.
Location Label Placement
| Storage Type | Label Placement | Label Size | Material Recommendation |
|---|---|---|---|
| Pallet rack | Front beam at each level, centered | 4×6 inches minimum | Reflective polyester or metal placard |
| Totem/Vertical labels | Upright column with all levels on one label | 8×12 inches or larger | Rigid plastic or metal |
| Shelving | Front edge of each shelf | 2×4 inches | Durable polyester or vinyl |
| Floor locations | Floor decal or low signage | 6×6 inches | Non-slip floor laminate |
| Aisle signs | Overhead or endcap at eye level | 12×18 inches | Rigid plastic, retroreflective for visibility |
Best practices for label durability:
- Thermal transfer printing on polyester or polypropylene for resistance to abrasion and chemicals
- Reflective or high-contrast materials for low-light conditions
- Protective laminates for harsh environments (cold storage, outdoor, high-traffic)
- Magnetic backing for metal racks in environments where adhesives fail (extreme cold, dusty surfaces)
Color Coding and Visual Cues
Many warehouses enhance location labels with color-coded zones to improve visual navigation:
- Blue = Bulk storage
- Green = Forward pick zones
- Yellow = Replenishment zones
- Red = Quarantine or restricted areas
- Orange = Hazardous materials
Color-coded rack levels (each shelf a different color) reduce picking errors by giving operators an instant visual check.
Barcode Standards for Location Labels
Location labels typically use Code 128 barcodes encoding the full location string. The WMS expects a specific format, so barcode scanning must return the exact alphanumeric identifier.
Design checklist for location barcodes:
- Readable at distance: 4×6 inch labels scannable from 3-5 feet; 6×8 inch for long-range scanners
- High contrast: Black bars on white or reflective background
- Human-readable text below barcode: Large, clear font (18-24 pt)
- Quiet zones: Maintain at least 0.25 inch clear space on both sides of barcode
- Orientation: Horizontal (ladder orientation) for rack labels to avoid scanning at awkward angles
Some warehouses add check digits to location IDs (e.g., using modulo-10 or Luhn algorithm) so the WMS can detect scan errors. If the scanned location fails the check digit validation, the system rejects it, preventing misplaced inventory.
Item-Level Barcoding
Item-level barcoding identifies individual products, cases, and master cartons as they move through the supply chain. Warehouses rely on standardized product identification to interface with suppliers, carriers, and customers.
Product Identification Standards (GS1)
GS1 is the global standards organization that defines product identification across retail, logistics, and healthcare. The primary identifiers are:
| Identifier | Length | Purpose | Example |
|---|---|---|---|
| GTIN-12 (UPC-A) | 12 digits | North American retail products | 012345678905 |
| GTIN-13 (EAN-13) | 13 digits | International retail products | 5012345678900 |
| GTIN-14 (ITF-14) | 14 digits | Shipping containers and cases | 10012345678902 |
| SSCC | 18 digits | Serial Shipping Container Code for logistics units | 000123456789012345 |
Each GTIN uniquely identifies a product at a specific packaging level. A single SKU might have:
- GTIN-12 (each/unit level) — individual candy bar
- GTIN-13 (inner pack) — box of 12 candy bars
- GTIN-14 (case level) — case of 24 boxes (288 candy bars total)
Case and Carton Labels (GS1-128)
GS1-128 shipping labels are the standard for B2B distribution. They combine a barcode with human-readable information about the contents. A typical GS1-128 label includes:
| Application Identifier | Data Element | Example Value |
|---|---|---|
| (01) | GTIN of case contents | 10012345678902 |
| (10) | Batch/Lot number | LOT2024A |
| (15) | Best before date (YYMMDD) | 260630 (June 30, 2026) |
| (37) | Count of trade items in case | 24 |
| (3103) | Net weight in kg (3 decimal places) | 005250 = 5.250 kg |
FEFO (First Expired, First Out) and lot traceability depend on capturing this data at receiving. A single GS1-128 scan provides all critical attributes without manual data entry.
Master Carton and Pallet Labels
For multi-case shipments, warehouses apply master carton labels or pallet labels:
- Master carton: Outer container holding multiple inner cartons (e.g., a "corrugate" box holding 4 cases)
- Pallet label: Applied to stretch-wrapped pallet containing mixed or uniform cases
These labels often include:
- SSCC (Serial Shipping Container Code): Unique 18-digit identifier for the logistics unit
- Ship To / Ship From: Address blocks
- Carrier routing: Carrier-specific barcode (UPS MaxiCode, FedEx PDF417)
- PO Number: Purchase order reference
- Gross weight and dimensions
The SSCC is crucial for ASN (Advance Ship Notice) workflows — the sender transmits the SSCC and contents electronically, allowing the warehouse to pre-receive the shipment in the WMS before it physically arrives.
Internal Barcoding for Non-GS1 Items
Not all products in a warehouse have manufacturer-assigned GTINs — especially:
- Raw materials and components
- Work-in-process items
- Custom kitting and assemblies
- Returned goods awaiting disposition
For these items, warehouses assign internal SKU barcodes:
- Encode internal SKU number in Code 128 or Code 39
- Print labels on-demand as items are received or created
- Include human-readable SKU, description, and location
On-demand label printing (thermal printers at receiving, kitting, and packing stations) enables dynamic labeling for returns, repackaging, and exception handling.
Item-level barcodes only work if the WMS item master is synchronized with inbound shipments. When suppliers send GTINs that don't exist in the WMS, receiving grinds to a halt while staff manually research product codes. ASN integration and regular item master updates prevent these bottlenecks.
Barcode Scanning Hardware
Choosing the right scanning hardware is as important as the barcode standard itself. Different warehouse workflows demand different scanner types, connectivity, and ruggedness.
Scanner Categories
| Scanner Type | Form Factor | Read Range | Connectivity | Typical Use Case |
|---|---|---|---|---|
| Handheld Laser Scanner | Pistol grip | 0-50 cm | USB/RS232 tethered | Fixed receiving/shipping stations, high-volume close-range scanning |
| Handheld 2D Imager | Pistol grip | 0-60 cm | USB/wireless | General-purpose scanning of 1D and 2D codes, mobile workflows |
| Mobile Computer | Rugged handheld with touchscreen | 0-60 cm | Wi-Fi, cellular | Picking, putaway, cycle counting — full WMS integration on device |
| Ring Scanner | Wearable on finger | 5-30 cm | Bluetooth to wrist computer | Hands-free picking, high-volume putaway, order fulfillment |
| Vehicle-Mount Terminal | Forklift-mounted with large display | 1-10 m (long-range) | Wi-Fi, wired power | Forklift operators scanning racks, pallets, and locations from vehicle |
| Fixed-Mount Scanner | Stationary imager at conveyors/portals | 10-100 cm | Ethernet/industrial bus | Automated sortation, dock door portals, conveyor junctions |
Handheld Scanners (Tethered)
Corded handheld scanners are the workhorse of fixed receiving and shipping stations. They connect via USB or RS232 to a workstation and cost $100-$500 depending on performance.
Key selection factors:
- 1D laser vs 2D imager: Laser is faster for linear barcodes but cannot read 2D codes or damaged labels. Imagers handle both but cost 20-30% more.
- Scan rate: 100-300 scans per second for high-volume stations
- Durability: IP54-rated for dust/water resistance, drop ratings of 1.5-2 meters
- Decode algorithms: Ability to read damaged, low-contrast, or poorly printed codes
Best for: Receiving desks, shipping stations, will-call counters
Mobile Computers
Rugged mobile computers combine barcode scanning, touchscreen display, and wireless connectivity in a single device. They run Android or Windows operating systems and directly interface with the WMS via Wi-Fi.
Common models:
- Zebra MC9300 (rugged Android mobile computer for extreme environments)
- Honeywell CK65 (ergonomic cold storage model)
- Datalogic Memor 10 (lightweight Android with long-range scanner)
Features to evaluate:
- Battery life: 8-12 hour shifts require hot-swappable batteries or 5000+ mAh capacity
- Screen brightness: 500+ nits for outdoor or bright warehouse environments
- Scan engine: Standard range (0-50 cm) vs extended range (up to 15 meters for high racks)
- Operating temperature: Standard (-10°C to 50°C) or cold storage models (-30°C to 50°C)
- Drop/tumble specs: MIL-STD-810G certification for 1.8m drops onto concrete
Best for: Directed picking, putaway, cycle counting, mobile receiving
Ring Scanners and Wearables
Ring scanners (or finger-mounted scanners) free both hands for picking and handling items. They pair via Bluetooth to a wrist-mounted computer that runs the WMS picking application.
Advantages:
- Faster picking: No need to holster and draw a handheld scanner
- Ergonomic: Reduces wrist strain and repetitive motion injuries
- Hands-free: Operators can manipulate items while scanning
Common workflows:
- High-volume piece picking (e-commerce order fulfillment)
- Cross-docking with rapid scanning
- Putaway in dense pick zones
Popular models: Zebra RS5100 Ring Scanner, ProGlove MARK 3, Socket Mobile DuraScan
Best for: Piece pick, each-pick, high-velocity picking operations
Vehicle-Mount Terminals
Forklift-mounted terminals allow operators to scan while driving, eliminating the need to dismount for every pallet movement. They feature:
- Large, rugged touchscreens (10-12 inches)
- Integrated long-range scanners (up to 15 meters)
- Voice-directed picking integration (optional headset connectivity)
- 12-48V power from forklift battery
Best for: Pallet putaway, bulk picking, replenishment, inventory moves in high-bay warehouses
Fixed-Mount Scanners
Fixed-mount imagers are installed at strategic chokepoints:
- Dock door portals: Scan every pallet entering/exiting the warehouse automatically
- Conveyor junctions: Read and sort packages at high speed (up to 1000+ scans/minute)
- Shipping verification tunnels: 5-sided scanning (top, bottom, 3 sides) to capture all labels
Technologies:
- Presentation scanners: Operator places item in front of scanner (similar to grocery store checkout)
- Laser arrays: Multiple laser beams cover a wide scan zone
- Camera-based vision systems: Industrial cameras with image processing for complex reads
Best for: High-throughput automated operations, reducing manual scanning
All scanners must integrate with the WMS. Tethered scanners act as keyboard wedges (data appears as if typed). Mobile computers run WMS client apps over Wi-Fi. RFID readers require middleware to filter and route tag reads. Ensure the WMS vendor supports your chosen hardware platform before procurement.
Scanner Selection Decision Matrix
Resources
| Resource | Description | Link |
|---|---|---|
| GS1 Standards | Official GS1 barcode standards, Application Identifiers, and implementation guides | gs1.org/standards/barcodes |
| GS1-128 Barcode Generator | Free online tool to generate GS1-128 barcodes with Application Identifiers | gs1us.org/tools/gs1-company-database |
| Barcode Verifier Standards (ISO/IEC 15416) | ISO standard for barcode print quality grading | iso.org |
| Zebra Scanner Selector Tool | Interactive tool to choose the right Zebra scanner for your application | zebra.com/scanners |
| RFID Journal | Industry publication covering RFID technology, case studies, and implementation guides | rfidjournal.com |
Related Topics
- Warehouse Zones — how barcode scanning supports zone-based workflows
- Receiving & Putaway — LPN creation and location scanning in receiving
- Picking & Packing — barcode-directed picking and pack verification
- Inventory Management — cycle counting and inventory accuracy with barcode systems
- Shipping Labels — understanding carrier-specific barcode formats for outbound shipments