Codabar
A self-checking numeric barcode with start/stop letters, historically used by libraries and blood banks.
Codabar Specification
| Character set | Digits 0-9, $ - : / . + , plus start/stop characters A-D (or T N * E variants) |
| Data length | Variable; start and stop letters are not transmitted as data |
| Check digit | None required; optional Mod 16 and similar schemes exist for critical flows |
| Density | ≈5-8 characters per inch depending on ratio and X |
| Module width (X-dimension) | 0.19-0.50 mm typical |
| Print ratio | Wide:narrow 2:1 to 3:1 (2:1 or 3:1 common; 20:1 self-clocking variants excluded) |
| Magnification | Scales with X-dimension and ratio |
| Quiet zone | 10X on each side (6.4 mm minimum commonly recommended) |
| Standard | ANSI/AIM BC3; no current ISO symbology standard |
| Origin | Pitney Bowes (popularized by Monarch Marking Systems), 1972 |
| Sample data | A1234B |
Try It: Generate a Codabar Barcode
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What Is Codabar?
Codabar (also NW-7) is a variable-length, self-checking symbology from 1972, encoding digits 0-9 plus six symbols ($ - : / . +) with four start/stop characters (A B C D, or T N * E in some variants) chosen by the implementer. Each character is seven elements wide with exactly two wide — a structure that, like Code 39, makes most print defects fail loudly instead of decoding into wrong data.
Its historical footprint is remarkable for a format with no strong modern champion: US library circulation systems, American blood bank labeling, air waybills, and photo-finishing envelopes all ran on Codabar because it printed well on dot-matrix and impact printers of the era. It remains a fallback in specialized equipment. New general-purpose deployments are rare — Code 128 or Code 39 cover the same ground with better standardization — but Codabar knowledge stays essential wherever those legacy systems persist.
Common Applications
- US library circulation and book spine labels
- Blood bank and laboratory specimen tracking (legacy)
- Air waybills and parcel manifests (legacy)
- Photo finishing envelope tracking
Related Barcode Types
The classic self-checking alphanumeric barcode: 43 characters, simple structure, still everywhere in industry.
A digits-only inventory barcode with a single Mod 10 check digit, descended from the Plessey code.
A proprietary integer-only barcode from Laetus used to verify packaging and inserts in pharmaceutical production.
Codabar FAQ
What are the A, B, C, D in Codabar data?
Start and stop characters that frame the symbol. They are not transmitted — scanners strip them — but you must supply them when generating (A1234B is valid; 1234 alone is not). Different industries chose different letters as convention: libraries often used B...B or D...D, blood banks A...D. Any of the four works technically.
Is Codabar still a good choice for a new system?
Rarely. It has no ISO symbology standard, a character set narrower than Code 39, and no mandatory check digit. Choose it only when interfacing with legacy equipment that expects Codabar — libraries and some lab systems still do. For everything else, Code 128 (compact, standardized) or Code 39 (simple, self-checking) is the better foundation.