Quick answer: type the number – for example a library card number – optionally framed by the start and stop letters your system uses (A, B, C or D). If you leave them out, A and B are added. Then download the barcode or create a batch for a whole run of cards.
A barcode from 1972 that refuses to retire
Codabar was designed by Monarch Marking Systems for retail price labels and quickly spread to places that needed simple, self-checking numbers printed by modest equipment: libraries, blood banks, photo labs and courier airbills. It is also known as NW-7 in Japan, USD-4, Code 2 of 7 and ABC Codabar. Blood banks moved to ISBT 128 years ago, but libraries all over the world still issue Codabar cards and books with Codabar labels.
| Characters | 0–9 and - $ : / . + |
| Start/stop | A, B, C or D (sometimes written T, N, *, E) |
| Check digit | None required; mod 16 is an option |
| Typical length | 14 characters on library cards |
How to make a Codabar barcode
- Enter the data. Digits and the symbols - $ : / . + are allowed between the start and stop letters.
- Use the right start/stop letters. Some library systems use a specific pair (for example A…A or C…D). Type them if you know them; otherwise A…B is used.
- Optional check digit. Only if your system expects one.
- Download or batch. Paste card numbers into the bulk box to create a printable sheet.
Library barcodes
Many integrated library systems expect a 14-digit Codabar starting with 2 for patrons and 3 for items, followed by the library's code, a sequence number and a check digit calculated by the library system itself. If you are replacing cards, copy the existing number exactly – including the start/stop letters the old cards use – so scanners at the circulation desk keep working without changes.
Making a batch of library cards
- Export the next block of patron numbers from your library system, one per line.
- Paste them into “Make many barcodes at once”.
- Download the printable PDF on A4 or Letter, or a ZIP of PNG files if your card printer software places images itself.
- Scan a test card at the circulation desk before printing the whole run.
Print tolerance
Codabar was designed to be printed by impact and dot-matrix printers on price labels, so it tolerates thick or slightly blurred bars better than denser codes. A bar width of 0.25–0.33 mm and a height of 10–15 mm suit plastic cards and book labels.
Frequently asked questions
Are the start and stop letters part of my number?
They are part of the barcode, but most scanners are set to drop them before sending the number. Check your scanner settings if they appear.
What is the difference between Codabar and Rationalized Codabar?
Rationalized Codabar uses a fixed 2:1 or 3:1 ratio for wide elements and is what modern standards describe. All Codabar scanners read it.
Can Codabar hold letters?
Only the start and stop letters A–D. The data itself is numeric plus a few symbols.
Why does my library card scanner not read the new barcode?
Make sure you used the same start/stop letters and length as the old cards; some systems check them.