Free barcode generator

If a retailer or marketplace will scan the product at checkout, you need a GS1-issued UPC (12 digits, North America) or EAN-13 (13 digits, most of the world). Amazon requires GS1 codes for most categories. You buy the number from GS1, then generate the image here.

For your own warehouse, packing slips and inventory apps, Code 128 is the right choice: it encodes letters and numbers, is compact, and every scanner reads it. Code 39 is older and larger but still common on labels. ISBN is EAN-13 with a 978 or 979 prefix and is what bookstores and Amazon expect on books.

UPC and EAN numbers end in a check digit calculated from the other digits. Scanners use it to reject misreads. If you type 11 digits for a UPC or 12 for an EAN the generator adds the correct check digit; if you type the full number it verifies it and warns you if it is wrong.

Print black on white at 100% scale or larger. Do not stretch a barcode: scale it proportionally or regenerate it at the size you need. Leave blank space either side of the bars. For labels under 3 cm wide use Code 128 rather than Code 39. Test a printed sample with a phone scanner app before ordering labels.