SSCC label: the 18 digits, the GS1-128 barcode and the ship notice

What is an SSCC label?

An SSCC label identifies one logistic unit, a carton, a pallet or a parcel, with a number that no other unit carries. SSCC stands for Serial Shipping Container Code. GS1 defines it as the key for "an item of any composition established for transport and/or storage that needs to be managed through the supply chain", and the label that carries it is the GS1 Logistic Label. The SSCC is the single mandatory element on that label.

Three terms get mixed up. The SSCC is the number. GS1-128 is the barcode it is printed in, a subset of the Code 128 symbology. The label is the paper with the barcode, the human-readable digits and the address. In the words of the GS1 General Specifications, the SSCC "provides a link between the physical logistic unit and information pertaining to the logistic unit that is communicated between trading partners using Electronic Data Interchange". That link is the reason retailers ask for it: the number on the carton is the number in the EDI 856 advance ship notice.

The rules on this page are from the GS1 General Specifications, release 26.0 of January 2026, checked on 3 October 2026. Prefix lengths and capacities are GS1 US figures.

How the 18 digits are built

The extension digit, the prefix and the serial reference always add up to 17 digits, and the check digit makes 18. The extension digit has no fixed meaning. It increases the capacity of the serial reference by a factor of ten.

The length of the prefix decides how many numbers you have. With a 7-digit prefix, 17 minus 7 leaves 10 digits for the extension digit and the serial reference: 10 billion SSCCs. With a 9-digit prefix, 17 minus 9 leaves 8 digits: 100 million. A warehouse that ships 400 cartons a day on 250 days a year uses 100,000 numbers a year, so 100 million numbers last 1,000 years. Capacity is not the constraint. Keeping one counter across every warehouse, packing station and 3PL that prints labels under the same prefix is.

GS1 US advises assigning the serial reference sequentially and building no meaning into it. A range that stands for a warehouse today means nothing after a reorganization.

How the check digit is calculated

The last digit is computed from the first 17. GS1's rule has three steps: multiply the digits alternately by 3 and 1, starting with 3 at the first digit, add up the results, and subtract the sum from the nearest equal or higher multiple of ten.

For the SSCC in the figure, the first 17 digits are 0 0614141 000048291:

digit    0  0  6  1  4  1  4  1  0  0  0  0  4  8  2  9  1
weight   3  1  3  1  3  1  3  1  3  1  3  1  3  1  3  1  3
result   0  0 18  1 12  1 12  1  0  0  0  0 12  8  6  9  3

sum         = 83
next ten    = 90
check digit = 90 - 83 = 7

The full SSCC is 006141410000482917. A scanner and a receiving system both run this calculation, so a number with a wrong check digit fails at the dock and in the ship notice. The General Specifications require the verification in application software. GS1 publishes the same steps on its check digit page.

What the label carries

A GS1 Logistic Label has three building blocks, top to bottom, and only the bottom one is mandatory.

The information can also be grouped in up to three segments, by the moment it becomes known: carrier at the top, customer in the middle, supplier at the bottom. The supplier segment holds the SSCC and data known at packing, such as the GTIN, batch and dates. The customer segment holds what is known at order processing: the ship-to location, the purchase order number, routing instructions. The carrier segment holds the ship-to postal code and transport references.

Each barcode element starts with an application identifier (AI). The ones seen on shipping labels:

Barcode size and placement

The bars stand upright, perpendicular to the base of the unit. For pallets GS1 recommends two identical labels on adjacent sides, so one stays readable when the pallet is turned in the truck or the rack. The minimum X-dimension drops to 0.250 mm only when the unit is physically too small for 0.495 mm.

How the label and the ship notice fit together

The receiving dock scans the SSCC and looks up the ship notice that was sent ahead. GS1 US describes it as one scan at the receiving bay that is linked to a pre-received ASN of the contents. For that lookup the SSCC has to be in both places, character for character.

In an X12 856 the number sits in the MAN segment:

HL*3*2*P~
MAN*GM*00006141410000482917~

MAN02 has 20 characters: the application identifier 00 and the 18 digits. A guide that asks for 20 characters rejects the 18 digits alone, and the spaces printed under the barcode are not part of the number. Where the segment goes depends on the trading partner:

A unit that is broken down and repacked gets a new SSCC. A carton on a pallet keeps its own number, and the pallet gets another one.

When an SSCC may be used again

The rule in the General Specifications: an individual SSCC "must not be reallocated within one year of the shipment date from the SSCC assignor to a trading partner". Regulatory or industry requirements may extend the period. With the 100,000 numbers a year from the example above and a 9-digit prefix, reuse is 1,000 years away, so the practical rule is simpler: never reuse.

The failures come from elsewhere. A counter that restarts after a system migration, a second packing system that draws from the same range, and a label that is reprinted with a new number while the 856 still holds the old one all produce an SSCC that is on a label and unknown in the ship notice, or the reverse. Retailers check for exactly that mismatch: Kroger requires the ASN to be 100% accurate with respect to license plates, its term for the SSCC on the pallet. What retailers publish about penalties is collected under EDI compliance.

One naming point: the GS1 General Specifications never write "SSCC-18". The standard calls it SSCC. X12 guides say SSCC-18: Walmart's 856 guide lists MAN01 code GM as "SSCC-18 Bar code".

What this means for your integration

The SSCC is generated where the carton is closed: in a warehouse system, a shipping tool, at a 3PL or in the ERP. The ship notice is built somewhere else. The integration has to carry the number, with the carton's contents, from the packing record into the 856 before the truck leaves, and it has to check what it carries: 18 digits, a valid check digit, your own prefix, and a number not seen before.

We build that as part of an EDI integration: the pack data is read from the system that prints the labels, each SSCC is validated, the hierarchy is assembled per partner guide as described under EDI mapping, and a notice with a missing or duplicate SSCC is held and shown in the dashboard instead of sent. Tell us where your labels are printed.