How to Make a Barcode: Step-by-Step Free Guide

Step 1 — Choose the Right Barcode Format

This is the most important decision in the whole process. Get the format wrong and everything downstream — the number you choose, where you register it, how scanners read it — breaks. The table below maps your situation to the correct format:

Step 2 — Decide on Your Barcode Number

Before you can generate anything, you need to know what value to encode. This depends on which format you chose.

If you chose EAN-13 or UPC-A (retail)

These formats require a globally unique product identifier called a GTIN (Global Trade Item Number). To get one legitimately:

1. Register with your local GS1 member organization. They assign you a company prefix — typically 7 to 9 digits.
2. Using your prefix, assign a unique product reference number to each SKU you sell (each size, color, and variant gets its own number).
3. The last digit is a check digit, calculated automatically by an algorithm. A good barcode generator handles this for you — you only need to supply the first 12 digits (for EAN-13) or 11 digits (for UPC-A).

If you chose Code 128 (internal SKU)

You have complete freedom here. Define your own numbering scheme — for example:

• SHIRT-BLK-L-001 for a black large shirt, unit 1
• SKU-20260601-X for a date-based reference
• WH-A3-BIN-07 for a warehouse location label

There are no format restrictions, but consistency matters. Use the same prefix structure across the same product category so your inventory system can parse SKUs reliably.

If you chose QR Code

A QR Code can encode almost anything: a full URL (https://yourshop.com/product/123), plain text, a phone number, or a vCard. Shorter content scans faster, but QR Codes handle over 2,000 characters without issues. For product pages, use the canonical URL of that specific product — not the homepage.

Step 3 — Generate the Barcode (Free)

Once you have your numbers, generating the actual barcode image takes a few seconds. There are two workflows depending on whether you need one barcode or many.

Your barcode images are generated entirely inside your browser. No data is sent to any server, and nothing is stored. You can work with sensitive internal SKU numbers without any privacy risk.

Step 4 — Verify the Barcode Scans Correctly

Always verify before you commit to a print run. A barcode that looks correct visually may still fail to scan due to resolution issues, incorrect digit counts, or formatting errors.

Quick verification (phone scan)

On iPhone, open the Camera app and point it at the barcode image on your screen. On Android, use Google Lens. The decoded value should appear immediately and match exactly what you entered. If nothing appears after a few seconds, the barcode has an issue.

Professional verification (retail requirements)

If your product is going onto retail shelves, major supermarket chains typically require EAN-13 barcodes to meet an ANSI/ISO grade of C or above. A smartphone scan is not sufficient to verify this. Use a dedicated barcode verifier such as an Axicon or Webscan device to grade the symbol before submitting to your retailer.

Common generation errors to watch for

• EAN-13 entered with 12 digits: You may have omitted the check digit. A proper generator calculates and appends it automatically — just supply the first 12 digits.
• UPC-A entered with 13 digits: You likely entered an EAN-13 number. Select the EAN-13 format instead, or trim to 11 digits and let the generator add the check digit.
• Code 128 with invisible special characters: Copying from Excel sometimes pastes hidden characters (non-breaking spaces, tab characters). Paste your value into a plain-text editor first to strip formatting before generating.

Step 5 — Print the Barcode Label

The right printing method depends on your volume and whether the label is for a retail product, a shipping box, or internal warehouse use.

Avery label sheets (laser or inkjet printer)

Best for small batches, samples, and early-stage operations. Common choices: Avery 5160 (30 labels per sheet, 67×25 mm) for small product labels, and Avery 5163 (10 labels per sheet, 102×51 mm) for larger shipping or shelf labels. Download your PDF from Bulk Barcode Generator, open in Preview or Adobe Reader, select the matching Avery template, and print at Actual Size — never "Fit to Page," which rescales the barcode and can cause scan failures.

Thermal label printer (Rollo, Zebra, Dymo, Brother)

Best for medium to high volume, warehouse environments, or continuous production. Download the PDF at the correct label dimensions in millimeters. Connect the printer, load your label roll, and print at Actual Size. Thermal printing produces sharp, durable barcodes even in humid warehouse conditions.

Commercial printing (packaging or large runs)

If the barcode will be printed directly on product packaging, download the PNG at the highest available resolution and send it to your graphic designer. The designer places it into the packaging artwork at the correct minimum size, and the print shop reproduces it alongside the rest of the design. Make sure the barcode is printed at a minimum width of 31.35 mm (for EAN-13) to guarantee scan reliability on retail equipment.

Common Mistakes to Avoid

These are the errors that cause rejections, failed scans, and wasted print runs:

• ❌ Using Code 128 on a retail product instead of EAN-13 / UPC-A. Retail scanners and EDI systems expect GTINs. A Code 128 SKU will be rejected at the retailer's receiving dock.
• ❌ Buying barcodes from non-GS1 sources (eBay, "barcode resellers"). Amazon and most major retailers now verify GTIN ownership against the GS1 database. Barcodes from resellers fail these checks and can get your seller account flagged.
• ❌ Printing the barcode too small. The GS1 minimum for EAN-13 is 31.35 mm wide × 22.85 mm tall. Going below minimum size reduces scan reliability to unacceptable levels for retail use.
• ❌ Placing the barcode across a fold, seam, or curved surface. The bars distort and scanners cannot read them reliably. Print on a flat, unbroken surface.
• ❌ Printing dark bars on a dark background. Barcodes require high contrast between bars (dark) and spaces (light). Black on white or dark navy on kraft brown both work. Dark red on black does not.
• ❌ Scaling the PDF when printing. "Fit to Page" or "Shrink Oversized Pages" in your printer dialog will resize the barcode. Always select Actual Size (100%).