How To Print And Encode Size Codes For Shipping And Inventory Systems

Size Code An identifier printed or encoded on shipping packaging for the supply-chain purpose described by 'Size Code'. Implementing size codes correctly means choosing a durable printing method, appropriate encoding (1D, 2D, or RFID), and label placement that supports fast scans at receiving, cross-dock, and retail backrooms.

This article lays out practical, operational steps for warehouse managers and label suppliers who must deliver reliable size-code labels that integrate with WMS and retailer ASNs.

Label Content And Encoding Choices

Decide early whether the size code will be plain text only, part of a barcode, or encoded into an RFID tag. Consider environmental exposure: cold storage, moisture, or abrasion may require thermal-transfer printing or RFID instead of direct thermal labels.

• Direct Thermal Labels: Cost-effective for short-lived shipping labels but fade with heat and sunlight — acceptable for single-leg domestic shipments.
• Thermal Transfer Labels: More durable; use resin or wax-resin ribbons when labels must survive long transit, wet conditions, or storage.
• RFID Tags: Use for high-throughput distribution where pallets and cartons need bulk reads without line-of-sight.

Barcode Symbology And GS1 Compliance

If you encode the size code in a barcode, select symbology that is compatible with your scanning equipment and retail partners. For interoperability with retailers and carriers, GS1-compliant barcodes (GS1-128, GS1 DataMatrix) are recommended when the size code needs to be associated with GTINs or application identifiers (AIs).

• GS1-128: Ideal for encoding GTIN + application identifiers like lot, expiry, or count; good for pallet and carton labels.
• GS1 DataMatrix / QR: High data density for cases where label space is limited or multiple data elements are needed in a single symbol.
• Human-Readable Backup: Always print the plain-size text next to the barcode or under the AI string for quick manual verification.

Label Design And Placement

Consistent label placement speeds receiving. Use label templates with clear placement rules (e.g., short side of the carton near the top-right corner of the face seen by dock staff). Maintain minimum whitespace (quiet zone) around barcodes and avoid printing over carton seams or heavy corrugation.

• Placement Consistency: Standardize the location on cartons so automated scanners and handhelds find the code faster.
• Contrast And Font: Use high-contrast toner/ink and avoid decorative fonts for the human-readable size code string.
• Label Size: Ensure bar height and module width meet scanner tolerance for your chosen symbology.

Integration With WMS And ASNs

Work with IT to ensure that when a label is printed the size code is simultaneously written to the WMS and, if applicable, included on the ASN or EDI 856 sent to the retailer. This closes the loop: the expected size on the PO and ASN is what the scanner validates on receipt.

• Print-On-Demand Integration: Connect label printers to the WMS so each carton label prints with the correct PO/GTIN/size code and serial/lot where required.
• ASN Matching Rules: Configure receiving to auto-accept or flag cartons when the scanned size code matches the ASN-level packing list.
• Quality Control: Implement a sampling process to validate label legibility and barcode decode rates before cartons leave the pack line.

Validation And Operational Checks

Before scaling a new size-code scheme across facilities, run pilot tests across multiple lighting and scanning conditions. Track scanner read rates and exceptions, then iterate on label size, symbology, or placement. Train receiving teams to perform quick visual checks and to scan both the barcode and the human-readable size for cross-verification.

In short, the Size Code should be printed or encoded on shipping packaging using a durable label, an appropriate symbology, consistent placement, and linked in real time to WMS and ASN systems so warehouses and retailers can process shipments quickly and accurately.