GS1 Labeling for Retail: UPC, SSCC-18 & GS1-128 Explained

Labeling is where retail compliance becomes physically visible. Every carton that ships to a major retailer must carry a barcode label that uniquely identifies the carton, describes its contents, and links it to the electronic shipping data (ASN) that the retailer uses for automated receiving. Get the label right, and the DC scans, verifies, and puts away your product without intervention. Get it wrong, and every carton on every shipment generates a chargeback until someone diagnoses the root cause.

After two decades of configuring retail labels for 60+ retailers, we can tell you that labeling failures are among the most persistent compliance problems because they are systemic. A bad template, incorrect printer settings, or wrong placement procedure affects every carton. The fix is always the same: get the configuration right before the first shipment, validate it with test labels, and maintain quality control as an ongoing process.

This guide explains the barcode standards used in retail supply chains, what each major retailer requires, and the operational details that determine whether your labels pass or fail at the DC.

The Retail Barcode Hierarchy

Retail supply chains use multiple barcode standards at different levels. Understanding which barcode does what prevents the confusion that leads to labeling errors.

UPC (Universal Product Code)

The UPC is the product-level barcode—the one consumers see on store shelves and cashiers scan at checkout. It identifies a specific SKU: this exact product, in this exact size, in this exact variant. UPCs are assigned through GS1 US and are unique to each product. If you are selling to retailers, your products already have UPCs. The UPC is not what goes on your shipping labels—it identifies the product, not the shipping carton.

GTIN-14 (Global Trade Item Number)

The GTIN-14 identifies a case or inner pack of products. If you ship 12 units of a product in a case, the GTIN-14 tells the retailer's system “this is a case of 12 units of product X” without anyone needing to open the case. Target is notable for offering vendors GTIN-14 as one of three barcode options for shipping labels, alongside SSCC-18 and UPC-A.

SSCC-18 (Serial Shipping Container Code)

The SSCC-18 is the carton-level identifier that most major retailers require on shipping labels. Unlike UPC (which identifies a product type) or GTIN-14 (which identifies a case configuration), the SSCC-18 uniquely identifies a specific physical carton. No two cartons anywhere in the global supply chain should share the same SSCC-18.

The 18-digit structure is: extension digit (typically 0) + GS1 Company Prefix + serial reference number + check digit. Your WMS or labeling system assigns serial reference numbers sequentially and calculates the check digit using the Modulo 10 algorithm. The SSCC-18 on the physical label must exactly match the SSCC-18 in your EDI 856 ASN—this match is what enables automated receiving at the DC.

GS1-128 (UCC-128): The Barcode Symbology

GS1-128 is the visual encoding format—the symbology—used to represent SSCC-18 and other data on retail shipping labels. When retailers say they require “GS1-128 labels” or “UCC-128 labels” (an older term for the same thing), they mean labels printed in the GS1-128 barcode symbology carrying structured shipping data.

GS1-128 uses Application Identifiers (AIs) to define what each piece of data represents. AI (00) identifies the SSCC-18. AI (02) identifies the GTIN of the items in the carton. AI (37) indicates the quantity. These AIs are part of the barcode data and tell the scanner how to interpret each field.

What Retailers Require: Label Content by Retailer

Every retailer specifies different label content, formatting, and layout. Here is what we configure for three major retailers based on their current routing guides.

Walmart

Walmart requires specific WMIT field data on shipping labels and mandates STOP labels on mixed master packs (cases containing multiple SKUs). STOP labels must use Arial Bold 48pt font with three labels per carton placed on designated faces. Walmart's labeling requirements are detailed in their 408-page Supply Chain Packaging Guide. Barcode placement rules prohibit barcodes on the top of cases, and labels must be scannable through any shrink wrap covering the pallet.

Target

Target offers vendors three barcode options: SSCC-18, GTIN-14, or UPC-A. This flexibility is unusual among major retailers and reflects Target's approach to vendor accommodation. However, the choice must be consistent —you cannot mix formats across shipments. Target requires a formal label approval process before your first shipment, where sample labels are submitted for review and sign-off. Label placement follows standard right-side positioning with specific rules for cartons under 6 inches (label on top).

Dick's Sporting Goods

Dick's has some of the most detailed labeling requirements we have encountered. They use a zone-based label system with mandatory content in Zones A (vendor name and address), B (DC or store address), E (PO number with department number and name in 14-point bold—this must be the largest text on the label), and I (SSCC-18 barcode). The barcode specifications are precise: 4×6 inch label, 3.02-inch barcode length, 1.25-inch barcode height, 2:1 width-to-narrow ratio, with 0.25-inch quiet zones.

Dick's also requires thermal transfer printing —ink jet and laser are explicitly prohibited, and standard direct thermal does not produce labels durable enough for their scan requirements. New vendors must get label approval by mailing sample labels to Dick's Vendor Relations in Coraopolis, PA. And any vendor internal barcodes with 20 digits must be defaced with a vertical stripe if they do not match the UCC-128 label.

Label Placement Rules

Correct label placement is as important as correct label content. A label with perfect data and print quality will still generate a chargeback if it is in the wrong position on the carton.

The common pattern across most retailers: labels go on the right side of the carton when the carton is oriented with the opening facing up. Position the label 2 inches from the natural base (bottom edge) and 2 inches from the right vertical edge. For short cartons (typically 4 to 6 inches tall, with the exact threshold varying by retailer), the label goes on top, 2 inches from the right corner. For non-conveyable or oversized cartons (typically exceeding 48 inches in the longest dimension), the label goes on the end.

Universal placement rules that apply across most retailers: labels must never fold over a corner or edge, labels must never overlap a taped seam (the tape adhesive can interfere with scanning), labels must not be placed under shrink wrap or stretch film where the wrap creates wrinkles or distortion over the barcode, and if multiple labels are required on the same carton (some retailers require labels on two faces for non-conveyable items), they must all be identical.

Print Quality: Why It Matters More Than You Think

A barcode that scans perfectly in your warehouse can fail at the retailer's DC. The difference is environment and equipment. Your warehouse scanner may be newer, closer to the label, and in controlled lighting. The DC scanner may be automated, scanning from a fixed position as cartons move down a conveyor at speed, under different lighting conditions.

This is why retailers specify ANSI barcode quality grades. The ANSI verification process evaluates multiple parameters: symbol contrast (the difference between the bars and spaces), minimum reflectance (how dark the bars are), modulation (consistency across the barcode), defects (voids in bars or spots in spaces), and decodability (how close the barcode is to the theoretical ideal). A barcode graded ANSI C might scan 80% of the time in ideal conditions but only 60% of the time on a fast-moving conveyor—which means 40% of your cartons need manual processing.

Print quality is determined by four factors: printer settings (darkness/heat, speed, and resolution), label media quality (the face stock and adhesive), print head condition (worn heads produce degraded output), and printing method. Thermal transfer printing generally produces higher and more consistent ANSI grades than direct thermal because the wax or resin ribbon creates a more defined image that does not degrade over time.

Common Labeling Failures and How to Prevent Them

SSCC-18 Mismatch Between Label and ASN

The most common labeling compliance failure is not a printing problem—it is a data problem. The SSCC-18 on the physical label does not match the SSCC-18 in the EDI 856 ASN. This happens when the label generation and ASN generation processes are not synchronized. The fix is ensuring both systems pull from the same data source at the same point in the fulfillment workflow.

Faded or Degraded Barcodes

Labels that scan perfectly when printed but fail at the DC are typically direct thermal labels that have degraded during transit. Heat exposure in truck trailers, friction from cartons rubbing together, and UV exposure through trailer walls can all fade direct thermal images. The prevention is thermal transfer printing for any supply chain with transit times exceeding a few days or temperature exposure risk.

Incorrect Label Template

Using a Walmart label template for a Target shipment (or vice versa) happens when WMS configuration does not properly map retailer-specific templates to destination retailers. Automated template selection based on the retailer identified on the purchase order prevents this. Manual label template selection by warehouse staff creates ongoing error risk.

Wrong Placement

Labels placed on the wrong face of the carton, too close to the edge, over a seam, or folding over a corner. This is a training and standard work instruction issue. The routing guide placement specifications must be translated into visual work instructions with photos showing correct and incorrect placement for each carton size category.

Labeling as Part of the Compliance System

Labeling does not exist in isolation. The label content comes from the EDI purchase order data. The SSCC-18 on the label must match the ASN data. The label placement must follow the routing guide. And label quality must be maintained through the printer and media specifications in the routing guide. A labeling failure is often a symptom of a process failure upstream—incorrect EDI data, desynchronized ASN generation, or routing guide specifications that were not built into warehouse procedures.

We maintain label templates for 60+ retailers. When a new client onboards, we activate and validate the template for their specific retailers, print test labels, verify barcode quality with ANSI verification equipment, and confirm placement meets the routing guide before the first live shipment. That validation process prevents the systematic labeling failures that generate chargebacks on every carton until diagnosed.

If you are setting up retail labeling for the first time or experiencing labeling-related chargebacks, talk to our team. We can review your current setup, identify the root causes, and configure compliant labeling for your specific retailers.