Articles
The short version
What most people actually need to know
Barcoding looks like a deep technical field and mostly is not. Four ideas cover the great majority of real questions, and everything in the guides above is an elaboration of one of them.
A barcode is a way of writing a string. It carries no meaning of its own. A scanner reads the bars, works out the characters, and types them wherever the cursor happens to be — which is why a scanner behaves like a keyboard and why the string has to match something in your system to be useful.
The symbol and the number are separate purchases. Drawing a symbol is free, here and everywhere. Owning a retail product number is a licence from GS1, and no generator can grant it. Confusing the two is behind most of the money wasted on barcodes by small businesses.
Retail formats are rigid; internal formats are not. EAN-13, EAN-8 and UPC-A have fixed lengths, mandatory check digits and defined size ranges, because a supermarket till has to read them at speed with no context. Code 128 and QR codes have none of those constraints, which makes them the right tools for anything scanned only by you.
Most failures are physical, not digital. A code that will not scan has usually been cropped, scaled from a bitmap, printed too small or printed in the wrong colour. The file is rarely the problem, which is why the troubleshooting guide starts with the margin rather than the encoder.
Start here instead
If you just need a barcode
The generators do not require any of this reading. Pick the format that matches where the code will be scanned, type your value, and download the SVG. Come back to the guides when something does not behave as expected — a rejected marketplace listing, a scanner that beeps at everything except your label, or a supplier asking for a GTIN you are not sure you need.
New guides are added as questions come up repeatedly. If you have one that is not answered here, the tool pages carry FAQ sections covering the specifics of each format.
Vocabulary
Terms that come up constantly
- GTIN. Global Trade Item Number — the number itself, in 8, 12, 13 or 14 digit form. EAN-13 and UPC-A are barcode symbols that carry one.
- Symbology. The encoding scheme: EAN-13, Code 128, QR and so on. Choosing a symbology is choosing how the string is drawn, not what it means.
- X-dimension. The width of the narrowest bar. It sets how small a symbol can be printed and is the single most useful number when diagnosing a size problem.
- Quiet zone. The blank margin at each end of a symbol. Part of the code, not padding, and removing it breaks scanning outright.
- Check digit. A digit computed from the ones before it so that misreads and typos are detected rather than accepted.
- Magnification. Printed size as a percentage of a format's nominal dimensions. Retail symbols are valid between 80% and 200%.
- Human-readable interpretation. The digits printed under the bars, so a cashier can key the number in when a scan fails.