Logistics & Shipping • 100% Free & Browser-Based

Free Code 39 Barcode Generator

Classic alphanumeric barcode symbology widely used in US Department of Defense (LOGMARS) and automotive manufacturing.

11. Selected SymbologyISO/IEC 16388

Code 39

Code 39 — Alphanumeric barcode widely used in automotive, government, and industrial systems.

22. Enter Barcode ValueVALID ✅

ℹ️ 43 characters: 0-9, A-Z (uppercase only), and symbols (-, ., $, /, +, %, space)

⚙️ Barcode Sizing & Visual Style▼

Bar Width (2x)

Bar Height (px)

Quiet Zone Margin

Text Font Size

Bar Color

Background Color

Display Human-Readable Text

Text Position

Instant Barcode Preview

Vector Live Preview

Download Format:

TECHNICAL SPECCHECKSUM PASS

TYPE: Code 39

LENGTH: 10

DATA: CODE39TEST

What is Code 39 Barcode?

Classic alphanumeric barcode symbology widely used in US Department of Defense (LOGMARS) and automotive manufacturing. Defined under standard ISO/IEC 16388, Code 39 is engineered for fast, reliable optical scanning across industrial and commercial environments.

Specification	Details
Standard Symbology	Code 39 (ISO/IEC 16388)
Character Set	43 characters: 0-9, A-Z (uppercase only), and symbols (-, ., $, /, +, %, space)
Checksum Algorithm	Optional Modulo 43 check character
Quiet Zone Margin	Minimum 10 times the narrow bar width or 0.25 inches (6.35 mm)
Processing Mode	100% Client-Side In-Browser (Zero Server Logs)

✅ Key Advantages

•Self-checking symbology with high fault tolerance
•Simple encoding structure supported by virtually every legacy barcode reader
•Can be printed with special barcode fonts without algorithmic conversion

📦 Common Use Cases

•US Department of Defense military supply chain (MIL-STD-129 / LOGMARS)
•Automotive Industry Action Group (AIAG) parts labeling
•Hospital ID badges and specimen tubes
•Industrial inventory bins and machinery parts

📐Engineering Specification

Deep-Dive: How Code 39 Encodes Data

Code 39 (also designated "Code 3 of 9" and standardized under ISO/IEC 16388) is one of the most battle-tested linear barcode symbologies in industrial history. Developed in 1974 by Dr. David Allais and Raymond Stevens at Intermec, Code 39 earned its name because each character symbol is composed of 9 total elements (5 bars and 4 spaces), exactly 3 of which are wide. Because of its wide optical tolerances and self-checking architecture, it remains the mandated standard for US Department of Defense military supply chains (MIL-STD-129 / LOGMARS) and automotive manufacturing (AIAG).

⚙️ 43-Character Set & Discrete Element Architecture

Code 39 is a discrete symbology, meaning each character pattern is separated from its neighbor by an inter-character space:

›Standard Character Repertoire: Encodes 43 alphanumeric characters: 0–9, capital letters A–Z, and 7 symbols (-, ., $, /, +, %, and space).
›Start and Stop Delimiters: Every Code 39 barcode must begin and terminate with an asterisk character (*), which sets the direction and timing for the scanner.
›Wide-to-Narrow Ratio (N:W): The wide elements must be between 2.0 and 3.0 times the width of the narrow elements (typically 2.5:1 or 3.0:1) to ensure accurate threshold detection.
›Optional Modulo 43 Checksum: While Code 39 is self-checking, mission-critical applications (such as defense logistics and medical patient bands) can append an optional Modulo 43 check character for near-zero error tolerance.

🔬 Physical Barcode Anatomy & Zone Breakdown

Quiet Zones

Minimum 10 times the narrow element width (X-dimension) or 0.25 inches (6.35 mm) on both lateral ends.

Start Asterisk (*)

Standard 9-element pattern signaling the beginning of data stream.

Inter-Character Gaps

Narrow space between consecutive characters preventing optical merge errors.

Data Characters

Discrete 9-element patterns encoding alphanumeric information.

Optional Mod 43 Check Digit

Mathematical verification character for high-security applications.

Stop Asterisk (*)

Matching terminator pattern completing scanner read sequence.

🖨️ Production & Printing Best Practices

✔Because Code 39 requires 9 elements plus an inter-character gap per character, it produces wider barcodes than Code 128. If your label space is constrained, consider switching to Code 128.
✔Do not display the start/stop asterisks in the human-readable text unless specifically required by your organization’s specification.
✔Use high wide-to-narrow ratios (3:1) when printing on low-resolution corrugated cardboard to compensate for ink bleed.

📷

Optical Scanner Compatibility: Compatible with virtually every legacy and modern barcode reader manufactured since 1975, including laser wands, CCD guns, fixed-mount industrial scanners, and smartphone cameras.

Frequently Asked Questions

What is Code 39?

Code 39 (also called Code 3 of 9) is a discrete, self-checking linear barcode symbology capable of encoding 43 alphanumeric characters. Each character is represented by 9 elements (5 bars and 4 spaces), 3 of which are wide.