Code 128

Code 128 is a variable-length 1D (linear) barcode that can encode any of the 128 ASCII characters — including numbers, uppercase, lowercase, and punctuation. It packs more data per inch than UPC or EAN, making it ideal for transaction IDs, shipping tracking, and warehouse logistics.

When you see a long horizontal barcode at the bottom of a Walmart, Target, or Home Depot receipt, that’s almost always Code 128. It usually encodes a transaction code (Walmart’s TC#, Target’s REC#) plus the store/register/cashier identifiers, so customer service can scan it to instantly retrieve the original transaction.

Code 128 has three subsets (A, B, C) optimized for different character types. Subset C is particularly compact for purely numeric strings — it encodes pairs of digits as a single character, doubling the data density.

On a typical 80mm thermal receipt, a Code 128 barcode is about 70mm wide and 5-8mm tall.