Code 128 in detail

In short: Code 128 is a very dense 1D barcode that can represent all 128 ASCII characters. It is standard in logistics and shipping and suits your own inventory numbers.

In more detail: Each character consists of 11 modules (3 bars, 3 spaces). The code starts with a start character, contains the data, a checksum (modulo 103) and a stop character. There are three character sets: A (capitals and control characters), B (upper and lower case), C (digit pairs, very compact).

In detail

• Checksum: start value plus weighted character values, remainder on division by 103.
• Switching character sets: number sequences become half as long in set C.
• Use: shipping labels (GS1-128 with application identifiers), inventory, libraries.
• Readability: observe the quiet zone (at least 10 times the module width), sufficient height, contrast.
• Own numbers: the inventory tool on this site creates codes like EZ-XXXX-XXXX and draws them as Code 128 (set B).

See also: Barcode types at a glance, Barcode scanners: technology and types