Code 128Linear (1D)Introduced 1981

Code 128B

Code 128 locked to code set B — the full printable ASCII range including lowercase letters.

Code 128B Specification

Character set	Full printable ASCII 32-127: digits, upper and lowercase letters, punctuation, and space
Data length	Variable; no fixed minimum or maximum
Check digit	Mandatory Mod 103 check character, appended automatically
Density	≈12 characters per inch at the minimum 0.19 mm X-dimension
Module width (X-dimension)	0.19-0.50 mm typical
Print ratio	Variable-width bars and spaces
Magnification	Scales linearly with the chosen X-dimension
Quiet zone	10X on each side
Standard	ISO/IEC 15417
Origin	Ted Williams, Computer Identics, 1981
Sample data	Hello World!

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What Is Code 128B?

Code 128B is Code 128 restricted to code set B, which covers ASCII values 32-127: all printable characters including lowercase a-z, uppercase A-Z, digits, and punctuation. It is the go-to locked subset for alphanumeric data that mixes upper and lower case but contains no control characters and little or no long numeric runs.

Code set B is the most commonly used single subset because human-readable identifiers — names, e-mail-like codes, license keys — live in the printable ASCII range. Compared with Code 39, Code 128B encodes the same alphanumeric content in roughly 60-70% of the width, while also carrying a mandatory check digit that Code 39 lacks.

Common Applications

Mixed-case alphanumeric identifiers
License keys and serial numbers with letters
General labeling where control characters never occur

Code 128Linear (1D)

A high-density, variable-length linear barcode that encodes all 128 ASCII characters, and the backbone symbology of modern logistics.

Code 128ALinear (1D)

Code 128 locked to code set A — uppercase letters, digits, and ASCII control characters.

Code 128CLinear (1D)

Code 128 locked to code set C — digit pairs packed two per character for maximum numeric density.

Code 128B FAQ

What is the difference between Code 128B and Code 128 auto?

Code 128B stays in code set B for the entire symbol. Code 128 auto starts in whichever subset fits and may shift — for example into code set C for a long digit run — to compress the symbol. For typical mixed-case text both produce nearly identical output; auto is preferable when the data may contain long numeric sequences.

Can Code 128B encode an ASCII DEL or control character?

No. Code set B tops out at ASCII 127 and excludes control characters below 32. Data containing control characters requires code set A or the FNC4 shifting mechanism of full Code 128 — in practice, use Code 128 (auto), which handles this automatically.

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