GS1-128 and SSCC Shipping Label Requirements
Short Answer
A GS1-128 shipping label carries logistics data in Code 128 with an FNC1 character, where every field is introduced by an Application Identifier. The critical one is AI 00, the 18-digit SSCC that uniquely identifies a carton or pallet. Retailer routing guides then add their own placement, content, and quality rules.
What GS1-128 Actually Is
GS1-128, formerly called UCC/EAN-128, is not a separate symbology. It is Code 128 with rules. A symbol qualifies as GS1-128 when an FNC1 character appears immediately after the start character, which tells the scanner that the data that follows is structured as GS1 Application Identifier elements. Everything else is ordinary Code 128 encoding, with subsets A, B, and C selected to compress the data.
That distinction matters in practice. A printer or label design tool that can produce Code 128 is not automatically producing a compliant GS1-128 symbol. If the leading FNC1 is missing or the field separators are wrong, the bars will scan and the data will be meaningless to your customer parsing engine.
Application Identifiers: The Grammar Inside the Barcode
An Application Identifier is a two to four digit prefix that declares what the following data means and how it is formatted. Predefined fixed-length fields need no terminator. Variable-length fields must be closed with an FNC1 separator, encoded as ASCII 29, whenever another field follows in the same symbol. Getting that separator wrong is the single most common encoding defect we see.
| AI | What it carries | Format |
|---|---|---|
| 00 | SSCC, the license plate for a logistic unit | 18 digits, fixed |
| 01 | GTIN of the trade item | 14 digits, fixed |
| 02 with 37 | GTIN of items contained, plus the count of them | 14 digits fixed, count up to 8 digits |
| 10 | Batch or lot number | Up to 20 characters, variable |
| 11 and 17 | Production date and expiration date | 6 digits YYMMDD, fixed |
| 21 | Serial number | Up to 20 characters, variable |
| 400 | Customer purchase order number | Up to 30 characters, variable |
| 410 and 420 | Ship-to GLN and ship-to postal code | 13 digits fixed, postal code variable |
| 3103 | Net weight in kilograms, three decimal places | 6 digits, fixed |
The SSCC-18 and Why the Check Digit Matters
The Serial Shipping Container Code is the identifier the whole shipping process hangs on. It is 18 digits: an extension digit chosen by the company, the GS1 company prefix licensed to you, a serial reference you assign to fill out 17 digits, and a check digit calculated with the standard modulo 10 method that weights alternating positions by three and one.
Three rules cause most of the trouble. The SSCC must be unique to one logistic unit, so it identifies that specific pallet or carton, not the product on it. It must not be reused for at least twelve months after shipment, and longer in regulated supply chains. And the SSCC on the label has to match the SSCC transmitted in the advance ship notice, because that is how the receiving dock links the physical unit to the electronic record. A mismatch there is a chargeback waiting to happen, even when the barcode itself is perfect.
Most WMS platforms generate SSCCs automatically from a configured prefix and a rolling serial. Confirm the prefix is your licensed one, confirm the check digit is calculated rather than typed, and confirm the counter does not reset when a site is rebuilt. Our page on label printing from SAP, Oracle, and your WMS covers where that number is created and how it reaches the printer.
The GS1 Logistic Label and Its Three Zones
The GS1 Logistic Label is a layout standard, not just a barcode. It is organized into three stacked sections, top to bottom:
- Carrier zone at the top – free format information applied at or near the time of shipment, such as the from and to addresses, carrier name, routing, and any carrier-specific marks.
- Customer zone in the middle – information known when the order is packed: purchase order, ship-to details, department, contents description, and similar text.
- Supplier zone at the bottom – the barcode area, containing information known at packing time, with the SSCC symbol as the lowest barcode on the label.
Common label sizes are A5 and A6 in metric regions and 4 by 6 inches in North America. Keeping the SSCC in the bottom zone is not decoration; scanners and automated readers on a dock expect to find it there.
Human-readable interpretation
Every barcoded field needs a human-readable interpretation near the symbol, with the Application Identifiers shown in parentheses. Those parentheses are display only and are never encoded in the bars. Data titles such as SSCC, GTIN, or BEST BEFORE go alongside the values so a person can read the label when a scanner fails. For the SSCC, the human-readable line is usually set larger than the rest because it is the number people read aloud in a dispute.
Bar Height, X-Dimension, Quiet Zones, and Placement
These are the requirements that get skipped when someone shrinks a label to fit stock they already have.
- Bar height – the SSCC symbol on a logistic label is specified at a substantial height, typically about 32 mm or 1.25 inches, so it can be read by a fixed scanner as the unit moves past.
- X-dimension – the narrow element width has a defined range for GS1-128 on logistic labels. Printing below the minimum to squeeze in more data is a reliable way to fail verification.
- Quiet zones – a clear margin of at least ten times the X-dimension on both ends of the symbol, free of text, borders, and print. Crowded quiet zones cause more no-reads than any other layout mistake.
- Pallet placement – apply the label so the SSCC sits roughly 400 mm to 800 mm above the base when height allows, at least 50 mm in from vertical edges, and place labels on two adjacent sides so the unit can be read from either approach.
- Carton placement – keep the symbol clear of the bottom edge and of vertical edges, off seams, tape, and shrink wrap folds, and never wrap a symbol around a corner.
Print Quality Is Part of the Requirement
A GS1-128 label is only compliant if the symbol grades acceptably when measured to ISO/IEC 15416. The GS1 General Specifications set a minimum overall grade for logistic labels, and most trading partners simply adopt it. Quiet zone violations, low contrast from a worn printhead, and ribbon wrinkle are the usual reasons an otherwise correct label fails. See barcode print quality grading and verification for what each parameter measures and why a scanner reading the label proves nothing.
Retailer Routing Guides Add Their Own Rules
GS1 defines the data structure. Your customer defines everything else, and their routing guide wins. Expect requirements for specific label size and stock, a mandated position on the carton, particular text blocks such as department number or store number, font sizes for human-readable data, the exact AIs they want present, and a rule that the SSCC on the carton must match the ASN. Some retailers also require a specific verification grade and reserve the right to ask for reports. Read the current version of the guide for every account rather than assuming last year applies.
Where GS1-128 Labels Go Wrong
- Missing leading FNC1 – a valid Code 128 symbol that no GS1 parser accepts as GS1-128.
- Wrong separators – variable-length fields not terminated, so the next AI is swallowed into the previous field.
- Reused or duplicated SSCC – two live pallets with the same license plate, which corrupts receiving records at both ends.
- Label content mismatched to the ASN – correct symbol, wrong relationship, and an automatic chargeback.
- Undersized symbols and crowded quiet zones – a layout problem the printer cannot fix.
- Wrong media for the environment – direct thermal labels sent through a cold chain or outdoors, faded before receiving.
How PCI Helps with GS1-128 and SSCC Labels
PCI has been building industrial label applications since 2001, and compliance labels are a large part of that. We look at the data first, then the layout, then the hardware, because a printer cannot correct a structural encoding error. Our industrial label printing consulting team reviews your GS1-128 data strings and label design against the standard and against your customer routing guides, and barcode printing process optimization tightens the workflow that produces them. When the fix is hardware, we size barcode and thermal label printers for the media, width, and duty cycle your shipping lanes actually run, and we can add label output validators so a bad symbol never leaves the building. Send us a sample label and we will tell you what your customer will find.
Need Your Shipping Labels to Pass?
Send us a sample label and the routing guide you have to satisfy. We will review the GS1-128 data structure, the SSCC, the layout zones, and the print quality, then tell you exactly what needs to change.
Frequently Asked Questions
Is GS1-128 the same thing as Code 128?
Not quite. GS1-128 is Code 128 used under GS1 rules. The symbol must begin with an FNC1 character right after the start character, and all data must be structured as Application Identifier elements with correct separators. Any Code 128 encoder can print bars that scan, but only a compliant GS1-128 symbol will parse correctly at your customer receiving dock. That is why testing with a plain scanner app can give you false confidence.
How is the SSCC-18 check digit calculated?
The SSCC is 18 digits: an extension digit, your licensed GS1 company prefix, a serial reference that fills the number out to 17 digits, and a check digit. The check digit uses the standard GS1 modulo 10 method, multiplying digits alternately by three and one from the right, summing them, and subtracting from the next multiple of ten. Your WMS or label software should calculate it, never an operator typing a number.
Can we reuse an SSCC number?
Not for at least twelve months after the unit ships, and many supply chains expect longer. The SSCC identifies one specific logistic unit, so a reused number can collide with a shipment still moving or still on someone books. Design the serial reference range large enough that reuse never becomes tempting, and make sure the counter survives a system rebuild or a site migration rather than restarting from zero.
Where exactly should the SSCC label be placed on a pallet?
The guidance is to place the label so the barcode sits roughly 400 mm to 800 mm above the pallet base when the load is tall enough, at least 50 mm in from the vertical edges, on two adjacent sides. That way a forklift or dock scanner reads the unit from either approach. Avoid stretch wrap folds and seams over the symbol, and never let a label wrap around a corner.
Does a retailer routing guide override the GS1 standard?
They work in layers. GS1 defines how the data is structured and encoded; the routing guide defines label size, position on the carton, which fields must appear, human-readable formatting, and often a minimum verification grade. Customers can add requirements but cannot change the encoding rules. When the two seem to conflict, follow GS1 for structure and the routing guide for everything visible, and ask the customer compliance contact in writing.
What print quality grade do GS1-128 shipping labels need?
The GS1 General Specifications set a minimum overall grade for logistic labels measured to ISO/IEC 15416, and most trading partners adopt that figure directly rather than writing their own. Some retailers set a higher bar in their routing guide. The practical answer is to verify with a conforming verifier at the aperture and wavelength your customer specifies, keep the reports, and treat a passing grade as the floor rather than the target.