What is the SSCC-18 Structure?
An SSCC is an 18-digit, non-intelligent number. This means the number itself doesn't describe the products inside the box; instead, it acts as a unique license plate that links to database records detailing the contents.
The 18 digits are broken down into four parts. The first digit is the Extension Digit, used to increase the capacity of the serial reference. This is followed by the GS1 Company Prefix, assigned by GS1 to the manufacturer. The third section is the Serial Reference, assigned sequentially by the shipper. The final number is the Modulo 10 Check Digit.
- Extension Digit (1 digit)
- GS1 Company Prefix (7-10 digits)
- Serial Reference (Variable length to make 17 total digits)
- Check Digit (1 digit)
How SSCC Connects to EDI and ASNs
The real power of the SSCC lies in its integration with Electronic Data Interchange (EDI). When a supplier builds a pallet, they generate an SSCC and place a barcode label on the shrink wrap.
They then send an Advance Ship Notice (EDI 856) to the retailer. This electronic document lists the SSCC and exactly what products, batch numbers, and quantities are on that specific pallet. When the truck arrives, the receiving dock worker scans a single barcode—the SSCC—and their warehouse system instantly ingests the entire pallet's contents without having to open it.
How to Calculate the Modulo 10 Check Digit
The 18th digit of an SSCC is a calculated check digit. It exists to ensure the barcode was scanned correctly and the number wasn't mistyped. It is calculated using the Modulo 10 algorithm based on the preceding 17 digits.
The steps are: First, number the positions 1 through 17 from left to right. Multiply the digits in the odd positions (1, 3, 5...) by 3. Multiply the digits in the even positions (2, 4, 6...) by 1.
Sum all these resulting products together. Finally, find the number required to add to that sum to reach the nearest multiple of 10. That number is your check digit.
Calculation Example: Modulo 10
Let's calculate the check digit for the 17-digit base: 00123456000000001.
Odd positions multiplied by 3: (0x3)+(1x3)+(3x3)+(5x3)+(0x3)+(0x3)+(0x3)+(0x3)+(1x3) = 0+3+9+15+0+0+0+0+3 = 30.
Even positions multiplied by 1: (0x1)+(2x1)+(4x1)+(6x1)+(0x1)+(0x1)+(0x1)+(0x1) = 0+2+4+6+0+0+0+0 = 12.
Total sum = 30 + 12 = 42.
The next multiple of 10 after 42 is 50. Therefore, 50 - 42 = 8. The check digit is 8. The full SSCC is 001234560000000018.
Frequently asked questions
Is an SSCC the same as a GTIN?
No. A Global Trade Item Number (GTIN) identifies a specific trade item or product SKU. An SSCC identifies a unique logistic unit, like a specific pallet or mixed shipping container.
Can I reuse an SSCC number?
GS1 rules state that an SSCC must not be reused for at least one year after the shipping container was dispatched, ensuring unique traceability.
What barcode format is used for an SSCC?
SSCCs are always encoded in a GS1-128 barcode format, prefixed by the Application Identifier (00).
Who assigns my Company Prefix?
Your GS1 Company Prefix is licensed directly from the GS1 member organization in your country (such as GS1 US).