Barcode fit calculator

How many characters fit in a barcode at a given label width, print density and module width — module geometry measured from our own engine.

A 4 inch label at 203 dpi is 812 dots wide. At a module width (X) of 2 dots:

† quiet zone already included in the measured width

How the number is produced

Width in dots = (fixed modules + modules per character × characters + quiet zone) × X. In ZPL the module width X is what ^BY sets, and it is measured in printer dots — so the same barcode is physically narrower on a 300 dpi head than on a 203 dpi one. The label width you enter is converted with inches × dpi and rounded down.

What this does not tell you

• Whether a scanner will read it. That depends on print quality, ribbon and media, and on the minimum X your application's specification requires — read that specification, not this page.
• Height. Only width is calculated here; the human-readable text under a barcode adds height, not width.
• Encoding shortcuts. Code 128 packs digit pairs into one character in subset C, so a numeric payload can fit in fewer characters than the table suggests; the table assumes one character per input character.

Generate a barcode · Try it in the ZPL viewer · Dots, mm and DPI migration