Free GS1-128 barcode generator.

Type

Linear; a subset of Code 128 reserved for GS1 data

Specification

GS1 General Specifications, section 5.4 (Release 26.0, 2026); Code 128: ISO/IEC 15417

Start pattern

Start character A, B or C, then FNC1

Character set

GS1 subset of ISO/IEC 646: 82 characters (digits, letters, 20 symbols), no space

Data capacity

48 data characters including AIs and separators; longer data needs a second symbol

Maximum length

165.10 mm including quiet zones

Check character

Modulo 103, added by the generator, not shown in the text line

X-dimension

0.495–0.940 mm on logistic units; 0.495–1.016 mm on trade items in general distribution

Bar height

At least 31.75 mm in general distribution

Quiet zone

10X left and right

AIs starting with 00–03, 11–13, 15–17, 20, 31–36 or 41 have a predefined length, so the next AI follows directly. All others must end with a separator (FNC1) if another AI follows, even fixed-length ones such as (422) country of origin.

For a case with GTIN 19521234543210, expiry date 31 December 2026 and batch ABC123, type 01195212345432101726123110ABC123. No FNC1 is needed, because the only variable-length field comes last.

A pallet of 40 such cases that is not traded as a unit lists its content under (02) and the count under (37). Type 02195212345432103740\F10ABC123, where \F ends the count. The example numbers use GS1 Prefix 952, reserved for examples.

The pallet's SSCC ends with a check digit, calculated like the GTIN check digit:

1. Take the first 17 digits (extension digit, GS1 Company Prefix and serial reference): 09521234567890123.
2. Multiply them alternately by 3 and 1, starting with 3 on the left, and add the products: 135.
3. Subtract it from the next equal or higher multiple of ten: 140 − 135 = 5, so you enter 00095212345678901235.

• Whole printer dots: use a module width of whole dots, such as 4 dots (0.500 mm) at 203 dpi or 6 dots (0.508 mm) at 300 dpi. At 0.495 mm and 300 dpi, the generated image mixes 5- and 6-dot modules.
• Width: at 0.495 mm an SSCC symbol is 77.2 mm wide and 87.1 mm with both quiet zones, so it fits an A6 label (105 mm wide).
• Margins and height: by default the downloaded image has no quiet zone and bars shorter than 31.75 mm. Leave 10X of white space on each side and stretch it vertically only; if the text distorts, hide it and set it in your layout.
• Text line: AIs in parentheses, a clear font such as OCR-B, at least 2 mm high (3 mm on GS1 logistic labels).
• Orientation: on cartons and pallets in general distribution the bars must stand upright, so do not rotate the symbol by 90° to save space.
• Verification: check prints with an ISO/IEC 15416 verifier. The GS1 minimum for cartons and pallets, 1.5/10/660, means grade 1.5 (C) or better with a 0.254 mm aperture at 660 nm.

• Typing the parentheses. The generator encodes them as data, so scanners send (01)… instead of 01… while the printed text looks right. Leave them out; the text line gets them automatically.
• No FNC1 after a variable-length field. 10ABC1232112345 reads as one batch number, ABC1232112345, not batch ABC123 plus serial number 12345. Type 10ABC123\F2112345.
• \F without escape sequences. The barcode then holds a backslash and an F, and the backslash is not in the GS1 character set. Switch on Escape sequences and use a capital F: \f is a form feed.
• Wrong or missing check digit. The generator prints a 13-digit GTIN under (01) or a mistyped last digit as entered. Calculate the check digit first.
• (01) for pallet contents. A logistic unit that is not a trade item lists its contents under (02), with the SSCC and the count (37). (01) and (02) must not share a unit.