Free Barcode Generator — Create UPC, EAN, CODE128 Barcodes Online

Every physical product sold in retail needs a barcode. Every warehouse needs barcode labels for inventory tracking. Every library needs barcodes on books. But generating barcode images should not cost money or require signing up for yet another SaaS tool.

Our free barcode generator creates high-resolution barcode images directly in your browser. It supports UPC-A, EAN-13, CODE128, CODE39, EAN-8, ITF-14, and more. No server uploads, no watermarks, no limits. Just enter your data, pick your format, and download.

Barcode Basics — How They Work

A barcode encodes data as a series of parallel lines (bars) of varying widths. Barcode scanners read these width patterns and decode them back into numbers or text. The concept dates to 1952 (patented by Norman Woodland and Bernard Silver), but barcodes did not see widespread retail adoption until the 1970s when UPC was standardized.

There are two main categories: 1D barcodes (the classic lines) and 2D barcodes (like QR codes, which encode data in a grid). This guide focuses on 1D barcodes — the linear bar-and-space format used in retail, logistics, healthcare, and manufacturing.

Our built-in processing engine renders barcodes entirely in your browser using standard encoding algorithms. Your data stays on your device. This matters for businesses encoding proprietary SKUs, product identifiers, or internal tracking numbers.

Barcode Types Explained — When to Use Each One

Choosing the wrong barcode format is the most common mistake beginners make. Here is a clear guide:

Format	Characters	Length	Primary Use
UPC-A	Numbers only	12 digits (fixed)	North American retail products
EAN-13	Numbers only	13 digits (fixed)	International retail, Amazon
EAN-8	Numbers only	8 digits (fixed)	Small retail products (limited space)
CODE128	Full ASCII	Variable	Shipping labels, inventory, general purpose
CODE39	A-Z, 0-9, symbols	Variable	Government, military, automotive (legacy)
ITF-14	Numbers only	14 digits (fixed)	Outer cartons, case-level shipping

If you are unsure, use CODE128. It is the most flexible format — it encodes any character, produces compact barcodes, and is readable by virtually every modern scanner.

Retail Barcodes: UPC-A and EAN-13

If you sell products in stores (or on Amazon), you need UPC-A or EAN-13 barcodes. These are the barcodes cashiers scan at checkout. Here is how they work:

UPC-A (Universal Product Code)

The standard for North American retail. Exactly 12 digits. The first 6-10 digits are your GS1 company prefix (assigned when you register with GS1), the next digits identify your specific product, and the last digit is a check digit calculated automatically. You must purchase a GS1 company prefix from GS1 before creating retail UPC barcodes. The prefix costs $250+ for an initial set of numbers. Our tool generates the barcode image — GS1 provides the valid numbers.

EAN-13 (European Article Number)

The international equivalent of UPC-A, used worldwide and required for Amazon product listings. Exactly 13 digits. A UPC-A is actually a subset of EAN-13 (prefix the UPC with a leading zero and you get the EAN-13 equivalent). If you sell internationally or list on Amazon, EAN-13 is the format you need.

Important: Do not make up random numbers for retail barcodes. Randomly generated UPC/EAN codes will conflict with existing products in retail databases and will be rejected by stores and Amazon. Always use numbers assigned through GS1 or an authorized reseller.

Internal Use Barcodes: CODE128 and CODE39

CODE128

The workhorse of internal barcode systems. CODE128 encodes the full ASCII character set — uppercase and lowercase letters, numbers, and special characters. It automatically selects the most compact encoding (Code A, B, or C subsets) for your data. Use CODE128 for:

• Warehouse inventory labels (encode SKU numbers, bin locations)
• Shipping labels and tracking numbers
• Asset tags (laptops, equipment, furniture)
• Employee ID badges
• Library books (internal catalog numbers)
• Event tickets and admission badges

For internal use, you can encode whatever numbering system makes sense for your operation. No GS1 registration needed.

CODE39

An older format still used in government, military (Department of Defense LOGMARS), and automotive (AIAG) applications. Encodes uppercase letters A-Z, digits 0-9, and a handful of special characters (-, ., $, /, +, %, space). CODE39 produces wider barcodes than CODE128 for the same data, so it requires more label space. If you are not in a legacy system that mandates CODE39, use CODE128 instead.

Sell Custom Apparel — We Handle Printing & Free Shipping

Printing and Resolution Guide

A barcode that looks good on screen can fail to scan when printed. Print quality is the number one cause of barcode scanning failures. Here is what matters:

• Resolution: 300 DPI is the professional standard for barcode labels. Thermal label printers (Zebra, DYMO, Brother) typically print at 203 DPI, which works fine for most barcodes. Avoid printing barcodes on standard inkjet printers when possible — ink can bleed and blur the bars.
• Contrast: Black bars on white background gives the best scan reliability. Avoid colored bars or colored backgrounds. Light-colored bars on dark backgrounds (reversed) will not scan on most readers.
• Quiet zone: Leave at least 10x the narrowest bar width as blank space on both sides of the barcode. This white margin is critical — without it, scanners cannot detect where the barcode starts and ends.
• Substrate: Glossy surfaces can cause glare that interferes with scanning. Matte labels work best. If you must use glossy, test with your specific scanner.

Sizing Your Barcode for Labels

Barcode sizing follows specific guidelines depending on the format and application:

Format	Minimum Width	Minimum Height	Notes
UPC-A	1.469" (37.29mm)	1.02" (25.91mm)	GS1 specification (80% magnification)
EAN-13	1.494" (37.95mm)	1.02" (25.91mm)	GS1 specification (80% magnification)
CODE128	Varies by data length	0.5" (12.7mm) min	Height should be at least 15% of width or 0.5", whichever is greater
ITF-14	5.61" (142.5mm)	1.25" (31.75mm)	For outer shipping cartons

Rule of thumb for CODE128: make the barcode at least 1.5 inches wide and 0.5 inches tall for reliable scanning with handheld scanners. Taller barcodes are easier to scan — increase height if you have the label space.

Use Cases by Industry

Retail and E-Commerce

UPC-A or EAN-13 for product packaging. Every physical product needs one if it is sold in stores or on major marketplaces. Print directly on packaging or apply adhesive labels. If you sell handmade products at farmers markets or craft fairs and want to accept credit card payments via Square or Shopify POS, adding a CODE128 barcode to your tags speeds up checkout.

Warehouses and Logistics

CODE128 for bin labels, pallet tags, pick tickets, and packing slips. Print batches of sequential barcode labels using a thermal printer. Many warehouse management systems (WMS) generate their own barcodes, but you might need to create labels for bins, shelves, or zones that the WMS does not cover.

Libraries and Archives

CODE39 or CODE128 for book spine labels, patron cards, and inter-library loan documents. Libraries have used barcode systems since the 1970s. If you are starting a little free library or community book exchange, barcode labels help you track which books are in circulation.

Events and Conferences

CODE128 on attendee badges for session check-in, meal tracking, and lead scanning. Print unique barcodes on each badge so exhibitors can scan attendees and capture lead information. Cheaper than RFID and works with any smartphone barcode scanner app.

Common Mistakes to Avoid

1. Using random numbers for retail UPC/EAN codes. These will conflict with existing products. Always get legitimate GS1-assigned numbers.
2. Printing barcodes too small. A barcode that is too narrow will not scan. Follow the minimum size guidelines above.
3. Choosing the wrong format. Putting letters in a numbers-only format (like UPC-A) will either fail or produce an invalid barcode.
4. Insufficient quiet zone. Trimming the white space around a barcode to save label space is a scanning death sentence.
5. Not test-scanning before bulk printing. Print one label, scan it with your actual scanner, and verify the data before printing thousands.
6. Low-resolution printing. Consumer inkjet printers at 150 DPI produce fuzzy bars that scanners struggle to read. Use at least 203 DPI (thermal) or 300 DPI (laser).

Frequently Asked Questions

What barcode format should I use for retail products?

For products sold in North American retail stores, use UPC-A (12 digits). For international retail or Amazon listings, use EAN-13 (13 digits). Both require a GS1 company prefix — you purchase your number range from GS1, then generate the barcode image with a tool like ours.

What is CODE128 and when should I use it?

CODE128 is a high-density barcode format that encodes any ASCII character — letters, numbers, and symbols. Use it for internal inventory labels, shipping labels, asset tracking, warehouse management, and any situation where you need to encode text (not just numbers). It is the most versatile barcode format.

Can I use these barcodes commercially?

The barcode images generated by our tool are yours to use however you want — commercially, personally, in any quantity. For retail product barcodes (UPC-A, EAN-13), you need to obtain valid number assignments from GS1 first. Our tool generates the barcode image; GS1 assigns the numbers.

What resolution should my barcode be for printing?

For standard label printing, 300 DPI is the professional standard. Our tool generates high-resolution images suitable for print. For thermal label printers (common in warehouses), 203 DPI is standard and works well. Always print a test label and scan it with your barcode scanner before printing a full batch.

Why does my barcode not scan?

Common reasons: the barcode is printed too small (minimum width varies by format — generally 1.5 inches for UPC-A), the print quality is low (inkjet bleed makes bars fuzzy), insufficient quiet zone (white space) around the barcode, or the wrong format was chosen (e.g., putting letters in a numbers-only format like UPC-A). Always test-scan before bulk printing.

Is this barcode generator free to use?

Yes, completely free with no limits. Unlike Barcode TEC-IT or Online Barcode Generator by Cognex, there are no watermarks, no account requirements, and no usage caps. The tool runs entirely in your browser — your data never leaves your device.