Generate linear barcodes with the right check digit and quiet zone, and download them as SVG or PNG.
Start here Choose the symbology your scanner or trading partner expects.
Any printable ASCII. The densest of the linear symbologies, and the usual default for internal labels.
Understand the format
A linear barcode is a width-encoded number: the scanner measures ratios between bars and spaces, which is why quiet zones and print quality matter more than size.
A laser or camera scanner sees a one-dimensional signal of light and dark and measures the relative widths of the bars and spaces. It never measures absolute millimetres, so a symbol can be printed large or small as long as the ratios survive. What it cannot recover from is a missing quiet zone: the blank margin either side tells the decoder where the symbol begins and ends, and cropping it is the single most common cause of a label that will not scan.
Each symbology also carries start and stop patterns so the scanner can detect orientation and read the symbol in either direction. That is why the pattern this page generates is longer than the data alone would suggest.
Retail symbologies build in a check digit computed from the other digits, using a weighted modulo-10 sum defined by the GS1 general specifications. A scanner recomputes it and rejects the read if it disagrees, which is what makes misreads rare. This page calculates that digit for you, and if you supply one that does not match it reports the mismatch rather than silently encoding a barcode that no retailer will accept.
Code 128 works differently: it carries a modulo-103 check symbol that the scanner verifies and then strips, so it never appears in the decoded data. Code 39 has an optional modulo-43 check character which, if you add it, is returned as part of the data for the receiving system to remove.
Use Code 128 for anything internal: it encodes the full printable ASCII set and packs digits two per codeword, making it the most compact of the linear formats. Use EAN-13 or UPC-A only with a GS1 company prefix you have been allocated, because those numbers identify a product globally and are not yours to invent. ITF-14 identifies a carton of retail units rather than a single item.
Code 39 remains common in older industrial and defence systems because almost every scanner reads it without configuration, but it is the least dense format here: every character costs nine elements. Codabar survives in libraries, blood banks, and photo labs, and has no check digit of its own.
Step by step
Barcodes are generated and rendered entirely in your browser. No data is uploaded, and downloads are produced locally from the same pattern shown on screen.
Worked examples
Input
590123412345
Result
5901234123457
The thirteenth digit is derived from the other twelve. Note also that the first digit is never drawn as bars: it is encoded in the parity pattern of the left half.
Input
00123456789012345678
Result
145 modules instead of the 233 that subset B alone would need
Subset C packs two digits into each codeword, so a long run of digits takes roughly half the width.
Reference
| Symbology | Encodes | Check digit | Typical use |
|---|---|---|---|
| Code 128 | All printable ASCII | Modulo 103, hidden from the data | Internal labels, logistics, GS1-128. |
| Code 39 | A-Z, 0-9, - . space $ / + % | Optional modulo 43 | Older industrial and defence systems. |
| EAN-13 | 13 digits | Modulo 10, required | Retail products worldwide. |
| EAN-8 | 8 digits | Modulo 10, required | Packaging too small for EAN-13. |
| UPC-A | 12 digits | Modulo 10, required | Retail in the United States and Canada. |
| ITF-14 | 14 digits | Modulo 10, required | Shipping cartons of retail units. |
| Codabar | 0-9 and - $ : / . + | None built in | Libraries, blood banks, photo labs. |
Practical Guide
Troubleshooting
FAQ
Code 128. It handles letters, digits, and punctuation, it is the most compact linear format, and every modern scanner reads it without configuration.
Not for anything sold. Those numbers are allocated from a GS1 company prefix and identify a product globally. For internal use, choose Code 128 instead.
Retail symbologies require a check digit computed from the preceding digits. If you supply one that does not match, the tool reports the mismatch rather than encoding an invalid symbol.
SVG for anything printed: it stays sharp at any size and keeps the bar edges exact. PNG is convenient for a screen, a slide, or a document that will not take vector art.
Because UPC-A is an EAN-13 whose first digit is zero. Many scanners and libraries report the thirteen-digit form; both refer to the same product.
No. The pattern is computed in your browser and rendered as SVG in the page. Nothing is uploaded, so internal part numbers stay internal.
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