What Is a Barcode and How Does It Work?

A barcode is a simple way to store information in a visual pattern that machines can read. You’ve seen them on product packaging, shipping labels, and even event tickets. Each barcode is made up of lines, spaces, or shapes that represent numbers or letters.

How Scanners Read It

A barcode scanner shines light onto the barcode and measures how it reflects back. The pattern of dark and light areas is converted into digital data, which the scanner sends to a computer or point-of-sale system. This process happens instantly, making barcodes a fast way to identify items.

What Information It Contains

Most barcodes hold product identifiers, like a number linked to a database entry. That entry can include details such as product name, price, or stock level. In business, this makes tracking and managing items much easier.

1D vs. 2D Barcodes

• 1D barcodes (like UPC or EAN) are the traditional ones with vertical lines. They store limited information, usually just a product code.
• 2D barcodes (like QR codes) use squares and patterns to store much more data, such as URLs, contact details, or even payment information.

Where Barcodes Are Used

Barcodes are everywhere in business: retail checkout systems, warehouse inventory, logistics tracking, healthcare records, and event ticketing. They save time, reduce errors, and make operations more efficient.

Types of Barcodes Supported

Code 128

Common in logistics and inventory management. It can store letters, numbers, and symbols, making it flexible for shipping and tracking.

EAN-13

Widely used in retail products across the globe. It encodes 13 digits and is standard for international product labeling.

UPC-A

Popular in US and Canadian retail. It encodes 12 digits and is often seen on grocery and consumer goods packaging.

QR Code

A 2D barcode that stores more data than traditional barcodes. It’s used for marketing, payments, and quick access to websites or apps.

Barcode Standards and When They Apply

Choosing the right barcode format matters because different industries and use cases have specific requirements. Using the wrong format means scanners cannot read your barcode or it may not be accepted by retail systems.

UPC-A (Universal Product Code) is the standard for retail products sold in the United States and Canada. It encodes exactly 12 digits and is required for products sold through major US retailers including Walmart, Target, and Amazon. UPC barcodes must be registered with GS1 (the global standards organization) for commercial use — you cannot invent your own UPC numbers for retail products.

EAN-13 (European Article Number) is the international equivalent of UPC-A, used on products sold in Europe, Asia, and most of the rest of the world. It encodes 13 digits and is the global standard for retail product identification. EAN-13 is also registered through GS1.

Code 128 is a high-density alphanumeric barcode that can encode the full ASCII character set — letters, numbers, and special characters. It is widely used in logistics, shipping labels, warehouse management, and internal inventory systems where GS1 registration is not required. Code 128 is the most flexible format for non-retail applications.

Code 39 is an older, simpler format that supports uppercase letters, numbers, and a few special characters. It is used in automotive, defence, and healthcare industries that established their barcode systems before Code 128 became dominant. Less efficient than Code 128 but still widely supported by legacy scanning equipment.

QR Code (Quick Response) is a 2D matrix barcode that stores significantly more data than 1D barcodes — URLs, contact information, WiFi credentials, payment details, and plain text. QR codes are the format of choice for marketing materials, digital menus, business cards, and any use case where the barcode will be scanned by a smartphone camera.

For mockups, prototypes, and internal systems where GS1 registration is not required, any format that your scanning equipment supports works fine. Code 128 is the most practical choice for internal inventory and asset tracking.

Barcode Best Practices — Getting Reliable Scans

A barcode that looks correct visually may still fail to scan reliably in real-world conditions. These practical guidelines ensure your barcodes work consistently:

Minimum size — Barcodes need to be large enough for scanners to resolve the individual bars. For Code 128 and EAN barcodes printed on labels, a minimum width of 25mm and height of 15mm is generally recommended. QR codes work reliably at 2cm × 2cm minimum for smartphone scanning.

Contrast — Always print dark bars on a white or very light background. Never reverse a barcode (white bars on dark background) unless your scanner specifically supports it. Low contrast between bars and background is the most common cause of scan failures.

Quiet zones — Barcodes require clear white space (called a quiet zone) on both sides — typically 10 bar widths for 1D barcodes. Placing a barcode flush against a border, edge, or other printed element interferes with scanning.

Surface and material — Barcodes on glossy surfaces can cause scanner reflections. Matte finishes scan more reliably. Curved surfaces make scanning harder — keep barcodes on flat areas of packaging.

Test before printing in bulk — Always scan your barcode with the actual scanner or app that will be used in production before committing to a large print run. Different scanners have different tolerances for bar spacing, ink bleed, and damage.

SVG for print, PNG for digital — SVG (vector) format scales to any size without quality loss, making it ideal for print. PNG is better for digital display and embedding in documents where vector formats are not supported.

Related Tools

• QR Code Generator — Create QR codes for URLs and text
• Image Resizer — Resize barcode images for print
• JPG to PNG Converter — Convert barcode images to PNG
• Unit Converter — Convert measurements for packaging
• Color Picker — Pick colors for label design