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Free Online CODE 39 Barcode Generator

CODE39 Mode

Code 39 remains a staple in manufacturing, defense, and healthcare workflows that rely on robust, easy-to-read linear barcodes. Enter uppercase letters, digits, and approved symbols, then preview and export labels without desktop software.

1. Enter barcode data

0 entries · Blank lines ignored · Duplicate values detected

2. Choose barcode settings

Barcode preview

Download settings

What is a CODE39 barcode?

Code 39 (also called Code 3 of 9) is one of the oldest alphanumeric barcodes still in active use. It encodes capital letters, digits, and a small set of symbols with start/stop characters that make it forgiving for manual verification. Automotive suppliers, government forms, and hospital wristband systems still specify Code 39 when equipment compatibility matters more than maximum density.

Recommended generator settings

These defaults work well for preview and download. Adjust to match your label template or scanner tests.

Bar width Start at 2; increase only if scans fail at your print size
Height 100 px or taller for warehouse and logistics labels
Quiet zone Keep the default margin unless your spec defines a different quiet zone
Readable text Leave enabled when operators verify values manually
Output format PNG for design files; JPEG for documents and quick sharing

Practical examples

  • 123-CT-789
  • PART-9920
  • ASSET-0042
  • REV-A-2026

When should you use CODE39?

  • Industrial part numbers and work-in-process tracking on shop floors
  • Government and defense document labels that mandate Code 39
  • Healthcare specimen and asset labels on equipment limited to Code 39
  • Low-volume internal tags where scanner compatibility outweighs barcode density

Limitations and common mistakes

Switch to CODE128 when you need lowercase letters, richer ASCII, or tighter bar width for long values. Retail product labeling requires EAN or UPC symbologies instead.

  • Trimming quiet zones when cropping the image for a label layout.
  • Scaling the barcode unevenly so bar width ratios no longer match the generated image.

Related formats

CODE39 vs CODE128

Format Best for Supported data Key difference
Code 128 Warehouse and inventory labels where the encoded value mixes letters and numbers Printable ASCII (codes 33–126) Denser encoding with full ASCII subsets and automatic check digit.
Codabar Library checkout and inventory systems that still mandate Codabar A, B, C, or D 0–9 plus - $ : / . + within the start/stop frame.
Code 128 Set B Mixed-case SKU or order references on packing slips and pick lists Printable ASCII (space through ~, codes 32–126) Uppercase and lowercase letters with digits and punctuation.

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Printing and scanning notes

Printing

  • Allow adequate quiet zones; Code 39 start/stop characters need clear margins.
  • Print at a width where narrow and wide bars remain distinct on your printer.
  • Avoid truncating the human-readable text when operators verify codes manually.

Scanning

  • Enable Code 39 on scanners that ship with it disabled by default.
  • Some scanners require an asterisk start/stop in the data stream; this tool encodes standard Code 39 symbols.
  • Verify inter-character gaps if labels are printed on continuous dot-matrix stock.

Frequently asked questions

No. Code 39 uses uppercase A–Z only. Convert text to uppercase before generating.

Hyphen, period, dollar sign, slash, plus, percent, and space are supported alongside digits and uppercase letters.

Code 39 can use an optional modulo-43 check character, but many workflows omit it. This generator encodes the value you enter.

Decades of installed scanners and written standards in automotive, aerospace, and healthcare keep Code 39 in production lines.

Yes, spaces are allowed. Avoid leading or trailing spaces unless your spec requires them.

Code 128 typically produces a narrower symbol for the same data. Use Code 39 when your scanner fleet is already configured for it.

Yes. Place one value per line to create multiple Code 39 barcodes in a single session.