Code 39 Barcode Generator
Create Code 39 barcodes for automotive, defense, and industrial applications.
Uppercase letters, numbers, and special characters
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What is a Code 39 Barcode?
Code 39, also known as Code 3 of 9, is a variable-length barcode that can encode uppercase letters, numbers, and several special characters. Developed in 1974, it was the first alphanumeric barcode symbology and is still widely used in industries like automotive manufacturing, defense, and healthcare due to its simplicity and ease of implementation.
Code 39 is called 'Code 3 of 9' because each character is represented by nine elements — five bars and four spaces — of which three are wide and six are narrow. Its self-checking design means a single printing defect will not produce a valid but incorrect character, reducing misread risk even without a check digit. These properties made Code 39 the first barcode adopted by the US Department of Defense and the automotive industry, where it remains in active use today.
Code 39 is a predecessor to more modern formats like Code 93 and Code 128, but remains widely used in industries that have established standards around it.
Want to learn more about Code 39 barcodes? Read our complete guide to Code 39 for automotive, defense, and healthcare applications.
How to Use This Generator
Creating a Code 39 barcode is straightforward:
- Enter your alphanumeric data (uppercase letters A-Z, numbers 0-9, and special characters -. $/+%)
- Click 'Generate Barcode' to create your Code 39 barcode
- Customize appearance and enable check digit in advanced options (optional)
- Download your barcode as SVG, PNG (multiple resolutions), or PDF
Technical Specifications
Key technical details for Code 39:
| Data Capacity | Variable length — no fixed limit (practical limit depends on print width and scanner capability) |
| Character Set | 43 characters: uppercase A-Z, digits 0-9, and 7 special characters (- . $ / + % space) |
| Symbol Size | Variable width; each character is 12 narrow/3 wide modules (plus inter-character gap) |
| Check Digit | Self-checking — optional Modulo 43 check digit for added security |
| Error Correction | Self-checking symbology; no built-in error correction beyond the optional check digit |
| Standard | ISO/IEC 16388 |
Common Use Cases
Code 39 barcodes are essential for:
- Automotive manufacturing and parts tracking systems
- Defense and military logistics for equipment identification
- Healthcare patient identification and specimen labeling
- Government and federal document tracking (IRS, Social Security Administration)
- Name badges and event access credentials with alphanumeric IDs
Tips & Best Practices
Get the most out of your Code 39 barcodes:
- Keep encoded data short — Code 39 produces wide barcodes compared to Code 128, so longer strings may exceed your available label space.
- Enable the optional Modulo 43 check digit when data accuracy is critical, such as in healthcare or defense applications.
- Use a narrow-to-wide bar ratio of 1:2.5 or 1:3 for the best scan reliability. Ratios below 1:2 can cause read failures on older scanners.
- Ensure quiet zones of at least 10 times the narrow bar width on both sides of the barcode — Code 39 requires clear margins for the start/stop asterisk characters to be detected.
Test Your Barcode
After generating your Code 39 barcode, verify it scans correctly with your equipment before deployment. Use our free barcode scanner to test your codes instantly - simply scan with your camera or upload an image to ensure proper encoding and compatibility. Test your barcode with our free scanner.
Frequently Asked Questions
How to generate a Code 39 barcode?
Enter your text (uppercase letters A-Z, digits 0-9, and the special characters - . $ / + % and space) into the input field above, then click 'Generate Barcode.' The generator adds the required start and stop asterisk characters automatically. Customize the appearance if needed, then download your barcode as SVG, PNG, or PDF — all for free.
Is Code 39 still in use today?
Yes, Code 39 is still widely used in automotive manufacturing (AIAG standard), US Department of Defense logistics (MIL-STD-1189B), and healthcare specimen labeling. While newer formats like Code 128 offer higher density, Code 39's simplicity, self-checking property, and deep industry adoption mean it remains a practical choice for many organizations.
Is Code 39 royalty free?
Yes, Code 39 is completely royalty-free and in the public domain. There are no patents, licensing fees, or usage restrictions. Any individual or business can generate, print, and scan Code 39 barcodes without paying anyone. The symbology is standardized under ISO/IEC 16388 and is open for unrestricted use.
What is the difference between Code 39 and Code 128?
Code 39 supports only 43 characters (uppercase A-Z, 0-9, and 7 special characters), while Code 128 encodes all 128 ASCII characters including lowercase letters. Code 128 also produces a shorter barcode for the same data because of its higher information density. Choose Code 39 when your system already requires it; choose Code 128 when you need compact barcodes or lowercase support.
Does Code 39 support lowercase letters?
Standard Code 39 does not support lowercase letters — it only encodes uppercase A-Z, digits 0-9, and seven special characters. There is an extended variant called 'Full ASCII Code 39' that encodes all 128 ASCII characters by using pairs of standard characters, but it requires a scanner configured to interpret the extended encoding.
Is this Code 39 barcode generator free?
Yes, this Code 39 generator is free to use with no registration, no watermarks, and no usage limits. Create as many barcodes as you need and download them in SVG (vector), PNG, or PDF format. The barcode is generated entirely in your browser, so no data is transmitted to any server.