How a Barcode Number Is Generated

How a Barcode Number Is Generated

Once a company prefix has been assigned, the barcode number is built in fixed stages. Below is the sequence Sistem Patent Kalite uses when guiding a client through the first barcode setup.

Building the number from the assigned company prefix

Every barcode number starts with the company prefix issued to the manufacturer or brand owner. The company prefix identifies the firm, the remaining digits identify the item, and a final check digit validates the full string.

13-digit barcode example

The 13-digit GTIN is the most common retail barcode. It carries a country identifier (for example, 869 for Türkiye), a company prefix, an item reference assigned by the firm, and the check digit at the end.

9-digit barcode example

Suppose the 9-digit company barcode number 869XXXXXX has been assigned. The firm wants to number three items: 1 kg of pasta, 1 kg of rice, and 1 kg of flour. In that case, each item receives a unique GTIN that combines the company prefix with a sequential item reference.

Note: the check digit is calculated automatically by the barcode system, so there is no need to compute it manually.

Company prefix: for example, 12345.

Item number: a sequential number assigned by the firm, usually starting at 1 for the first item and continuing in order.

Common mistakes to avoid

Two errors that send GS1 applications back for revision: reusing the same item reference for a different product (each variant, size, and flavour needs its own barcode) and editing the check digit by hand. The check digit has to come from the generator; a mismatched check digit will fail at point-of-sale scanning and at retailer onboarding.

For a walk-through of the GS1 Türkiye application and number-allocation steps, contact Sistem Patent Kalite.