Why do Code 39 barcodes always start and end with an asterisk?

The asterisk (*) is the unique start and stop character for Code 39. It tells the scanner where the data begins and ends. While it's in the barcode, it's usually hidden in the text below.

Does Code 39 support lowercase letters?

Standard Code 39 only supports uppercase (A-Z). To use lowercase, you must use 'Full ASCII Code 39,' which is less efficient. For modern projects requiring lowercase, we recommend Code 128.

What is the '3 of 9' name referring to?

Each character in Code 39 is represented by 9 elements (5 bars and 4 spaces). Out of these 9 elements, exactly 3 are always wide—hence the name 'Code 3 of 9.'

Is a check digit required for Code 39?

No. Code 39 is 'self-checking,' meaning it has internal logic to prevent misreads. However, the HIBC (Healthcare) and LOGMARS (Military) standards require an optional Modulo-43 check digit.

Code 39 Barcode Generator

The world's most versatile legacy standard. Generate reliable alphanumeric barcodes for automotive, defense, and government asset tracking.

Industrial StandardsANSI MH10.8MSelf-CheckingVariable LengthLegacy Compatible

Create Self-Checking Code 39 Barcodes

Our generator produces high-precision Code 39 symbols that are compatible with every scanner ever made.

Symbolify

1. Enter Characters

Input your data. Code 39 supports uppercase letters (A-Z), digits (0-9), and special symbols like dashes and periods.

2. Toggle Check Digit

Choose whether to include a Modulo-43 check digit. While Code 39 is 'self-checking,' some industries require this extra layer.

3. Export for Assets

Download as an SVG for permanent engraving or a 3600px PNG for durable polyester asset tags.

ANSI/AIM Compliant

Optional Mod-43

Durable Asset Tracking

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The Reliability of Code 39

In a world of complex digital IDs, Code 39 stands out for its simplicity and ruggedness. It is the definitive "no-nonsense" barcode for industrial asset tracking and military logistics.

Self-Checking Architecture

Code 39 is naturally 'self-checking.' Its internal structure ensures that a single printing defect won't result in a different valid character, providing high security even without a check digit.

Universal Compatibility

As one of the oldest alphanumeric standards, Code 39 is compatible with 100% of barcode scanners in existence. It requires no complex software logic to decode, making it the 'fail-safe' choice.

Industrial Ruggedness

The wide bar-to-space ratio makes Code 39 highly resistant to 'bleed' or low-contrast printing. This makes it ideal for harsh environments like construction sites, engine bays, and warehouses.

Standardized for Defense

Code 39 is the foundation for the LOGMARS (Department of Defense) and HIBC (Healthcare) standards. It remains the mandatory format for many government and military supply chains.

Full Name

Code 3 of 9

Characters

Alphanumeric (Caps)

Standard

ANSI MH10.8M

Check Digit

Optional Modulo-43

Legacy ChampionSelf-Checking Logic

If it isn't broken, don't fix it.

While newer formats like Code 128 offer more density, Code 39 remains the primary standard for **NASA**, the **Automotive Industry (AIAG)**, and many state government systems. Its ability to be read by legacy hardware makes it the safest choice for long-term industrial projects.

ANSI & LOGMARS Compliant

The Anatomy of Code 3 of 9

Code 39 is named for its elegant geometric ratio. Each character is a fixed-width unit designed for maximum readability across all legacy hardware.

Start Character

* (Asterisk)

Every Code 39 barcode begins with an asterisk. This unique pattern tells the scanner to prepare for incoming data.

Data Characters

Alphanumeric

The core of the barcode. Each character is represented by 5 bars and 4 spaces, totaling 9 elements.

Optional Checksum

Modulo-43

While Code 39 is self-checking, high-security sectors like healthcare (HIBC) add this digit for 99.9% accuracy.

Stop Character

* (Asterisk)

The asterisk also marks the end. It ensures the scanner doesn't stop halfway through a damaged label.

3:9

Why is it called "3 of 9"?

Each individual character in this symbology is composed of 9 elements: 5 bars and 4 spaces. Out of those 9 elements, exactly 3 are always wide, while the remaining 6 are narrow. This consistent ratio is why Code 39 is so easy for even low-quality scanners to interpret accurately.

Symbology Profile

Width vs. Efficiency

Code 39 uses a 3:1 ratio of wide to narrow elements. While it takes up more space, it is significantly more tolerant of printing errors than the high-density Code 128.

Code 39 Tolerance

High Error Margin

Code 128 Tolerance

Low Error Margin

Code 39 vs. Code 128

If Code 128 is better for space, why use Code 39? The answer lies in simplicity and ruggedness. Code 39 is often the only format recognized by legacy hardware in defense and heavy industry.

Complexity

Code 39Very Low (Simple)

Code 128High (Complex)

Scannability

Code 39Bulletproof (Wide)

Code 128Precise (Dense)

Check Digit

Code 39Self-Checking

Code 128Mandatory Mod-103

Data Logic

Code 39Fixed Pattern

Code 128Dynamic Switching

The Decision Factor

Use Code 39 if your scanners are over 10 years old, or if you are printing onto low-contrast surfaces (like wood or matte plastic). If you need to fit long alphanumeric strings on a small label, switch to Code 128.

Industrial & Military Standard

Code 39 Frequently Asked Questions

Technical insights into alphanumeric encoding, industrial '3 of 9' structures, and legacy hardware compatibility.