GS1-128 Shipping Labels: The Complete Guide to SSCC Barcodes

Source: Walmart Supply Chain Standards 2023 (rev. 04/05/2023), pp. 43–51

Source: Target GS1-128 Shipping Label Guidelines; SSCC-18/UCC-128 Carton Label Guidelines

Source: Amazon North American Vendor Shipment Preparation & Receive Manual (rev. 07/2021)

Source: Home Depot Barcode Specifications (rev. 04/2017); RDC Supplier Requirements Guide (rev. 04/2022)

Source: Kroger Manufacturing Shipping Container Labeling Requirements (rev. 02/2018)

A GS1-128 barcode is a standardized barcode symbology used on shipping labels to encode structured data like Serial Shipping Container Codes (SSCCs), GTINs, dates, and purchase order numbers. It is based on Code 128 but adds Application Identifiers (AIs) that tell scanners how to interpret the encoded data. It was previously known as UCC-128 or EAN-128.

GS1-128 and UCC-128 are the same thing. UCC-128 was the original name used in North America, while EAN-128 was used internationally. In 2005, GS1 unified the naming under "GS1-128." If a retailer’s compliance guide references UCC-128 labels, they mean GS1-128.

Both use the same barcode symbology, but GS1-128 adds a FNC1 (Function Code 1) character at the start that tells scanners to interpret the data using GS1 Application Identifiers. Standard Code 128 encodes raw text without any structured meaning. You cannot use a plain Code 128 barcode as a GS1-128—the FNC1 character is required.

SSCC-18 stands for Serial Shipping Container Code, an 18-digit number that uniquely identifies a shipping container (carton or pallet). It is encoded in a GS1-128 barcode using Application Identifier (00). The SSCC links the physical container to the electronic ASN, enabling automated receiving at the retailer’s distribution center.

The standard size is 4 inches × 6 inches (101.6 mm × 152.4 mm). The GS1 standard minimum bar height is 1.25 inches (31.75 mm), though some retailers like Walmart allow 0.75 inches. Quiet zones must be at least 10 times the X-dimension on each side. Check each retailer’s specific barcode specs—for example, Kroger requires 0.8 inches and Amazon requires 1.00 inch minimum bar height.

Placement varies by retailer. The general rule is: place the label on a flat surface on the side of the carton, away from edges, seams, and tape. Walmart requires left of center on the longest side. Amazon requires the side panel away from seams. For pallets, most retailers require labels on at least two adjacent sides.

An Application Identifier is a numeric prefix in a GS1-128 barcode that identifies the type and format of the data that follows. For example, AI (00) means the next 18 digits are an SSCC, AI (01) means the next 14 digits are a GTIN, and AI (17) means the next 6 digits are an expiration date in YYMMDD format. AIs are shown in parentheses for human readability but are not encoded as parentheses in the barcode.

Non-compliant labels can result in chargebacks ranging from $200 to $500+ per shipment depending on the retailer. Walmart may refuse to receive the shipment entirely. Kroger charges $500 per non-compliant shipment. Beyond financial penalties, repeated non-compliance can impact your vendor scorecard and damage your trading partner relationship.

Yes. You need a GS1 Company Prefix to generate valid SSCC numbers. The company prefix is assigned by GS1 (apply at gs1us.org in the US) and is used as part of the SSCC-18 number structure. Without a valid company prefix, your SSCCs will not be globally unique and may conflict with other companies’ numbers.

ANSI grades measure barcode print quality on a scale from A (best) to F (fail). Most retailers require at least Grade C for barcodes printed directly on corrugated board, and Grade B for print-and-apply labels. Walmart explicitly specifies these grades. You should verify print quality with a barcode verifier, not just a scanner—a scanner only tells you if it can read the barcode, not whether it meets the quality standard.