GS1-128
GS1-128 is the barcode symbology GS1 defines for encoding variable, multi-field logistics data — GTINs, SSCCs, batch/lot numbers, expiration dates, quantities — onto a single barcode using a structured prefix system called Application Identifiers (AIs). It is the format printed on GS1 logistics labels for cartons, pallets, and shipping units, distinct from the UPC-A/EAN-13 symbologies used for fixed, item-level scanning at point of sale.
What GS1-128 encodes, and how Application Identifiers work
A GS1-128 barcode is built from one or more Application Identifiers (AIs) — a 2–4 digit prefix, shown in parentheses in human-readable text, that tells a scanner what data comes next and in what format. Common AIs:
| AI | Meaning | Example |
|---|---|---|
| (00) | SSCC — the logistics unit's serial number | (00)106141412345678908 |
| (01) | GTIN of the contained item | (01)00012345678905 |
| (10) | Batch or lot number | (10)LOT4471 |
| (17) | Expiration date (YYMMDD) | (17)270630 |
| (37) | Count of contained units | (37)24 |
Multiple AIs can be concatenated into one barcode, so a single scan at receiving can capture a carton's SSCC, the GTIN of what's inside, its lot number, and its expiration date at once — something a fixed-length UPC symbol was never designed to carry.
Where it's required
GS1-128 is the symbology printed on the GS1 logistics label required on cartons and pallets by most major grocery, mass, and home-improvement retailers. Its role in receiving is specific: the SSCC encoded in the barcode is what a warehouse scans and matches against the Advance Ship Notice the supplier transmitted ahead of the shipment, letting a pallet's full contents be confirmed without opening it.
That is a different job from a UPC-A or EAN-13 barcode, which encodes a single, fixed GTIN for scanning one consumer unit at a point-of-sale register. A carton needs GS1-128 because it needs to carry variable data — lot, expiration, quantity — that a point-of-sale symbology has no fields for.
Where labeling breaks in practice
Most GS1-128 failures are label-production problems, not conceptual ones: an AI encoded in the wrong order, a human-readable text line that doesn't match what the barcode actually encodes, low print contrast a scanner can't read, or a UPC-format label used on a case where a retailer's routing guide specifically requires GS1-128. Labeling violations are consistently one of the largest retailer chargeback categories, alongside late or inaccurate ASNs — which is why label verification is usually one of the first things a retailer's onboarding process tests before a new supplier ships live volume.
Frequently asked questions
What is GS1-128 used for?
GS1-128 is the barcode format used on shipping labels for cartons, cases, and pallets. It encodes GS1 identification keys — most often an SSCC, plus a GTIN, batch/lot number, expiration date, or quantity — using a structured Application Identifier system.
What is a GS1 Application Identifier?
An Application Identifier (AI) is a 2–4 digit prefix that tells a scanner what kind of data follows it and in what format — for example, (00) precedes an SSCC and (17) precedes an expiration date. AIs let one GS1-128 barcode carry several distinct data fields.
Is GS1-128 the same as an SSCC?
No. GS1-128 is the barcode symbology — the format. The SSCC is one of several GS1 identifiers it can encode, alongside a GTIN, lot number, or expiration date in the same barcode.
Why do retailers reject GS1-128 labels?
The most common causes are a mismatch between the encoded data and the human-readable text, print quality too poor to scan, incorrect Application Identifier structure, or using a UPC/EAN label where a retailer's routing guide requires GS1-128. Any of these can trigger a labeling chargeback.