Barcode Generator

Barcodes encode data into visual patterns of parallel bars and spaces with varying widths. Scanners read these patterns using light reflection—black bars absorb light while white spaces reflect it, creating a binary signal that translates back into numbers, letters, or symbols. Our generator creates industry-compliant barcodes compatible with standard handheld scanners, point-of-sale systems, and smartphone apps.

Different formats serve distinct purposes across industries. CODE128 encodes the full ASCII character set (128 characters total), making it ideal when you need letters, numbers, and special characters in a single barcode. It's compact and efficient for general-purpose labeling. EAN-13 (European Article Number) and UPC (Universal Product Code) are numeric-only formats specifically designed for retail—you'll find these on nearly every product in stores worldwide. The 13-digit EAN-13 stores a country code, manufacturer ID, product number, and check digit.

CODE39 handles uppercase letters A-Z, digits 0-9, and seven special characters (space, minus, period, dollar sign, slash, plus, percent). Manufacturing plants and logistics companies prefer it because of its simplicity and readability even when printed at low quality. ITF-14 (Interleaved 2 of 5) appears on corrugated cardboard shipping boxes—it encodes 14 digits representing the GTIN-14 global trade item number.

You'll use this tool when labeling inventory in warehouses or stockrooms—generate CODE128 barcodes with your internal SKU numbers (like "WH-2024-3891") and stick them on bins, shelves, or product boxes. Small businesses creating shipping labels can encode tracking numbers, order IDs, or customer references without paying for label software. Libraries and educational institutions often need CODE39 barcodes for book cataloging systems, asset tracking, or ID badges. Event organizers generate unique ticket barcodes for admission control (each attendee gets a distinct code like "EVENT2024-00523"). Manufacturing operations print barcodes for work-in-progress tracking, quality control checkpoints, and component identification throughout assembly lines. Retail stores sometimes need custom EAN or UPC barcodes for internal products that won't be sold through major distribution channels (bakery items, deli products, store-brand goods). Healthcare facilities use barcodes on patient wristbands, medication packaging, lab samples, and medical equipment for safety verification and audit trails.

The most frequent error is choosing the wrong format for your data. People try to encode lowercase letters in CODE39 (which only accepts uppercase), then wonder why validation fails. Solution: either switch to CODE128 or convert your text to uppercase first. Similarly, attempting to put letters into EAN-13 or UPC formats won't work—those are strictly numeric.

Printing barcodes too small causes scanner read failures. Someone generates a barcode at default settings (2px bar width, 100px height), shrinks it down to fit a tiny label, and suddenly scanners can't read it. The bars become too thin for the scanner's resolution. Always print a test at your actual label size and verify it scans before printing 500 labels. If scanning fails, increase bar width to 3-4px before printing.

Ignoring the quiet zone (blank margin around the barcode) creates problems. Barcodes need white space on both sides—typically 10 times the width of the narrowest bar, minimum 2.5mm (about 10 pixels). If you print edge-to-edge without margins, scanners struggle to detect where the barcode starts and ends. Our default 10px margin handles this, but don't reduce it to zero just to save space.

Using incorrect numbers for retail products is a legal issue. Some people generate random 12-digit numbers for UPC barcodes without realizing each UPC must be purchased and registered through GS1 (the global standards organization). Legitimate retailers check these numbers—if yours conflicts with an existing product or isn't registered, it'll get rejected. For retail products sold through distribution, buy official UPC numbers from GS1. For internal use only (warehouse inventory, shipping labels, tickets), generate whatever codes you need.

Barcode generation follows a precise encoding algorithm that converts your input text into a pattern of bars and spaces. Here's how CODE128 encoding works with the example "ABC123":

Step 1: The encoder selects the appropriate CODE128 subset. CODE128 has three subsets: A (uppercase, control characters), B (uppercase, lowercase, punctuation), and C (numeric pairs). For "ABC123", it starts with subset B for the letters.
Step 2: Each character maps to a unique bar pattern. "A" becomes the pattern 11010000100 (representing bars and spaces), "B" becomes 11001000100, "C" becomes 10010001000.
Step 3: For the numbers "123", the encoder switches to subset C to save space by encoding digit pairs. "12" encodes as one symbol, "3" encodes separately.
Step 4: A start symbol (11010010000) goes at the beginning, identifying this as CODE128.
Step 5: Calculate the check digit using weighted sums. Each character has a numeric value; multiply each by its position, sum all values, divide by 103, and the remainder determines the check character pattern.
Step 6: Add the stop pattern (1100011101011) at the end, signaling the barcode's termination.

When a scanner reads this barcode, it measures the widths of bars and spaces, decodes the patterns back into character values, verifies the check digit matches, and outputs "ABC123" to your computer or POS system. The entire process happens in milliseconds. Different formats like EAN-13 use different encoding schemes—EAN encodes each digit as a 7-bit pattern with specific left-side, right-side, and center guard patterns that include parity information for error detection.

Always download SVG format when printing labels larger than 2 inches wide or when you're unsure of final dimensions. SVG scales infinitely without pixelation—you can print the same file on a small 1-inch label or a 12-inch warehouse sign. PNG works fine for standard label sizes but gets blurry when enlarged significantly. For thermal label printers (Zebra, Dymo, Brother), PNG at 203 DPI or 300 DPI prints crisp barcodes.

Test your scanner's minimum bar width requirements before mass production. Handheld laser scanners typically need 2px minimum bar width, while smartphone camera scanners prefer 3-4px for reliable reads. Print three test labels at different widths (2px, 3px, 4px), scan them from various distances and angles, then pick the smallest size that scans consistently. This optimizes label space without sacrificing readability.

For high-volume inventory systems, use CODE128 with alphanumeric codes that embed metadata. Instead of just "12345", encode "LOC-A3-12345" where LOC-A3 indicates warehouse location A, aisle 3. Your scanner app or database can parse these components automatically. For batch tracking, include date codes: "PROD-20260115-0842" (product manufactured January 15, 2026, at 8:42 AM). This eliminates separate lookups and speeds up operations.

When printing on colored backgrounds, maintain 70% contrast minimum between bars and background. Black bars on white paper gives 100% contrast (ideal). Black on light gray or cream works fine. Avoid printing black bars on dark blue, purple, or red—scanners can't distinguish them reliably. If you must use colored labels, print white rectangles behind the barcode or use white label stock with colored borders.

The first commercial barcode system appeared in 1974 when a pack of Wrigley's gum was scanned at a supermarket in Troy, Ohio, using the Universal Product Code (UPC) format. IBM engineers developed UPC in the early 1970s after grocery industry groups requested an automated checkout system to replace manual price entry. The distinctive UPC-A format with 12 digits became the North American standard, encoding manufacturer and product identifiers plus a check digit for error detection.

Europe developed EAN (European Article Number, now called International Article Number) in 1976 as an extension of UPC, adding a 13th digit for country codes. This allowed products to carry globally unique identifiers—the first three digits indicate the country where the manufacturer is registered (USA is 000-019, Germany is 400-440, etc.). Both UPC and EAN use the same underlying technology but with different digit counts.

CODE128, introduced by Computer Identics Corporation in 1981, revolutionized logistics and manufacturing by supporting alphanumeric data in a compact linear format. Its variable-length capability and high data density made it perfect for shipping labels, inventory tracking, and document management. Modern applications include FedEx tracking numbers, USPS Intelligent Mail Barcodes, and pharmaceutical serialization codes required by FDA regulations.

GS1 (originally the Uniform Code Council) manages UPC and EAN standards globally. Companies must purchase barcode prefixes from GS1 to ensure uniqueness—a single-company prefix costs around $250-$2,500 annually depending on how many product codes you need. This system prevents duplicate barcodes that would cause checkout errors and inventory confusion across millions of retail locations worldwide.

Barcode specifications are governed by international standards organizations that ensure compatibility across hardware and software systems. The International Organization for Standardization (ISO) publishes ISO/IEC 15416, which defines print quality specifications and testing procedures for linear barcodes. This standard establishes grading criteria (grades A through F) based on parameters like edge contrast, modulation, defects, and decodability.

GS1, the global standards organization for supply chains, maintains official specifications for UPC, EAN, and related retail barcodes. Their General Specifications document (updated annually) defines encoding rules, symbol dimensions, quiet zone requirements, and application identifiers for product identification. Healthcare institutions should reference FDA regulations on Drug Supply Chain Security Act (DSCSA) requirements for pharmaceutical product serialization using 2D barcodes.

The American National Standards Institute (ANSI) publishes MH10.8M standards for barcode quality and symbology specifications used throughout North American logistics and manufacturing. Professional barcode verifiers (devices that grade print quality) use algorithms specified in these standards to measure parameters like symbol contrast, minimum reflectance, and edge determination—critical for ensuring barcodes scan reliably across different scanner types and lighting conditions.