Choosing the Right Barcode Format
CODE128 is the workhorse of modern barcoding: it encodes the full ASCII set at high density, which is why couriers, warehouses and ticketing systems standardize on it — if you're labelling inventory, assets, lockers or documents, start here. EAN-13 and UPC-A are the retail formats scanned at checkout worldwide and in North America respectively; their numbers carry a mathematically computed check digit, which this generator calculates for you from 12 (EAN) or 11 (UPC) data digits, or verifies if you supply the full number. CODE39 survives in older industrial and defense systems — uppercase letters, digits and a few symbols only.
For reliable scanning: keep the quiet zone (white margin) intact, print at 100% scale, and prefer higher bar-width settings for low-quality printers. Retail numbers must be licensed from GS1 to be globally unique — this tool renders any number scannably but cannot register it for you. Need a code phones can read natively? Generate a QR Code instead, or grab a UUID for unique internal IDs.