Barcode guides
Guides on making, sizing and printing barcodes: UPC, EAN, Code 128, QR and Data Matrix.
How to Get a UPC Barcode for Your Product
License a GS1 prefix, number each product, add the check digit, then make the barcode image.
Barcode Size Guide: UPC, EAN and 2D Code Sizes for Printing
The standard UPC and EAN size, the 80% to 200% range, bar heights and quiet zones, in one table.
How to Make a Barcode: A Step-by-Step Guide
Pick the right type, get a valid number, generate the image, size it and scan a test print.