Barcode Generator (EAN-13, UPC-A, Code 128)

What it is for

Shelf labels, inventory tags, order slips and products you sell need barcodes that scanners read the first time. This tool encodes EAN-13 and UPC-A (the retail codes) and Code 128 (letters, digits and symbols) and prints them at true size, including the white quiet zones that scanners need.

It calculates the GS1 check digit when you leave it out and verifies it when you type it. It does not register product numbers — retail numbers must come from GS1 — and it has no EAN-8, add-on codes, GS1-128 application identifiers or 2D codes other than QR.

Worked example

The default input 400638133393 as EAN-13 returns 4006381333931: the tool added check digit 1. The barcode has 95 modules at the GS1 nominal width of 0.33 mm, so with quiet zones it is 37.29 mm wide.

For UPC-A we entered the 11 digits 03600029145; the result is 036000291452 with check digit 2, again 95 modules and 37.29 mm.

The Code 128 example PO-2027-000123 with 15 mm bars on a sheet of copies gives 15 symbol characters and 167 modules, 56.1 mm wide. The code-set line reads BBBBBBBBCCCCCC: the letters and the first digits use code set B, then the tool switches to code set C, which packs the six trailing digits 000123 into three symbols. For a shelf code SHELF-A-03-17 the digit runs are too short to be worth a switch, so all 13 characters stay in set B (16 symbols, 59.4 mm).

How to read the result

• Encoded text: exactly what a scanner will read, including the check digit for EAN/UPC.
• Check digit: the GS1 mod-10 digit; empty for Code 128, whose mod-103 check character is hidden in the bars.
• Modules and Module width: the barcode's length in narrow bars and the width of one bar on paper.
• Width with quiet zones: the space the barcode needs on your label. Leave it free of other print.
• For Code 128, the symbol values and code sets show how the text was packed.
• Files: the page as PDF, SVG and PNG, plus the barcode alone.

Tips and common mistakes

• If you type all 13 digits and one is wrong, the tool reports a check-digit error instead of printing a barcode that will not scan.
• Keep magnification at 1.0 or above for checkout scanners; 0.8 is the GS1 minimum.
• Shorter bars still scan with hand scanners, but keep them as tall as the label allows.
• Code 128 accepts plain ASCII only — no accents or emoji.
• Long digit runs make Code 128 shorter: 000123 costs three symbols, not six.
• Print at 100 % and check the test square before printing a full sheet.

FAQ

Can I make a barcode for a product I want to sell in shops?

You can print it, but shops expect a GS1-licensed number. A self-invented EAN may clash with an existing product.

What is the difference between UPC-A and EAN-13?

UPC-A is EAN-13 with a leading zero. Scanners worldwide read both.

Why is my Code 128 shorter than I expected?

Even runs of digits are packed two per symbol in code set C, and the tool picks the switch points that give the fewest symbols.

Which size should I print?

For retail, magnification 1.0 (0.33 mm modules). For internal labels Code 128 at 0.30 mm modules works with most scanners.