Bulk Code 128 barcode generator

What Code 128 can hold

Code 128 can encode all 128 characters of the ASCII set, through three code sets. Set A has capital letters, digits, and control characters. Set B has capital and small letters, digits, and punctuation. Set C packs two digits into each pattern, so a long number takes about half the width. This tool picks the sets for you and accepts the letters, numbers, and symbols on a standard keyboard.

How wide a code gets

Every character takes 11 modules, where a module is the width of the narrowest bar. A code also has a start character, a check character, and a stop pattern of 13 modules. The standard asks for 10 modules of blank space on each side.

So the width of a code in set B is 11 × (characters + 2) + 13 modules, plus 20 for the blank space. A longer code means thinner bars on the same label.

SKU-0001 is 8 characters: 11 × 10 + 13 = 123 modules, and 143 with the blank space. On a 38.1 mm label with 1 mm of padding each side, 36.1 mm ÷ 143 = 0.25 mm for each bar.

Make SKU numbers in bulk

Open the Make a series tab. Type SKU- in Starts with, 1 in First number, 500 in How many, and 4 in Digits. You get SKU-0001 to SKU-0500, each a Code 128 label.

The check character

Code 128 ends with a check character: a weighted sum of the character values, divided by 103, with the remainder as the check. The tool adds it for you, and a scanner uses it to throw out a misread instead of passing on a wrong code.

Tips for codes that scan

• Keep codes short. Each extra character makes every bar thinner on the same label.
• Use one style for all your codes, so capital and small letters never mix by accident.
• Check the preview. If the tool warns that the bars are thin, use a wider label, a shorter code, or a QR code.
• For products sold in shops, use EAN-13 or UPC-A instead. See the EAN-13 page and the UPC page.

Questions

What is the difference between Code 128 and Code 39?

Code 39 is older and wider, and holds capital letters, digits, and a few symbols. Code 128 holds more characters in less space. Use Code 39 only when a system asks for it.

Can Code 128 hold small letters?

Yes. Code 128 holds both capital and small letters, and the tool keeps them exactly as you type them. Code 39 does not, so it turns letters into capitals.

Is a Code 128 the same as a UPC or an EAN?

No. UPC and EAN are retail number formats with 8, 12, or 13 digits and a fixed check digit. Code 128 is for any text you choose, such as your own product codes.

Checked on 11 November 2026.