A barcode is just a font for machines: parallel bars that encode a number or text the way letters encode sound. The “which one should I use?” answer is short (Code 128 for general use, EAN-13 for retail products), but the distinctions behind it decide whether your labels scan the first time — so this guide walks the formats that actually appear on products and cartons.
The formats that matter
- Code 128 — the workhorse. Encodes any text and digits, high density, used for shipping labels, inventory and logistics.
- EAN-13 — the global retail product code: 13 digits (12 you supply plus a computed check digit).
- UPC-A — the North American retail standard, 12 digits with a check digit. EAN-13 and UPC-A scanners interoperate.
- Code 39 — an older, simple alphabet format still required by some legacy systems and US government labels.
- ITF-14 — a dense box-level code used on outer cartons of products sold at retail.
The check digit question
EAN-13 and UPC-A codes are 12 or 13 digits, but you rarely type all of them: the final digit is a check digit computed from the others, and a scanner uses it to reject a misread or mistyped code before it ever reaches the till. A good barcode generator validates and computes that digit for you, and refuses to print codes where the check digit cannot be correct — which catches typos that would otherwise produce hundreds of bad labels.
Rendering at print quality
- Keep a quiet zone: empty space around the code, roughly ten times the narrow module width per side.
- Print at a module width a laser or thermal printer can hold — too thin bleeds into a solid bar.
- Test scan one proof label before printing a full roll; scanners fail differently than eyes.
A barcode rendered into a blurry label is worse than no barcode, because a register cannot sell the product at all. Most barcode tools sell vector-quality output; ours produces a high-resolution made-for-print PNG from your code.
Retail numbers come from GS1
Anyone can generate a barcode image, but retail EAN-13 and UPC-A numbers need to be globally unique or stores will refuse them (or, worse, a cashier’s scanner will ring up someone else’s product). Retail numbers are assigned by GS1 to companies; internal inventory, shipping and school-lab use can use any numbers you like. So generate freely for internal use, and buy the proper prefix before you strike a deal with a retailer.
