Code 128 is a high-density alphanumeric barcode capable of encoding all 128 ASCII characters. It uses three different character sets (A, B, C) to optimize space efficiency, with automatic switching between them. This makes it ideal for applications requiring compact barcodes with complex data.

Key Features

Character Set: Full ASCII 128 characters
Density: High (about 3.5 characters per cm in version C)
Check Digit: Mandatory modulo 103 checksum
Applications: Shipping labels, packaging, logistics

Technical Specifications

Code 128 includes start codes (A/B/C), a weighted checksum, and stop pattern. Version C encodes two digits per symbol character for maximum density. It requires a quiet zone of 10X minimum. GS1-128 (formerly UCC/EAN-128) is a specialized subset used in supply chains with application identifiers.