Barcode Generator — Code 128, EAN-13 & UPC-A

Use EAN-13 or UPC-A only if you're producing an actual retail product code (EAN-13 outside the US/Canada, UPC-A within them) — both require a registered manufacturer prefix to be genuinely unique in the real world. For anything else — internal tracking numbers, asset tags, order codes — Code 128 is the most flexible choice since it encodes any printable ASCII text compactly. Code 39 is a reasonable alternative where a simpler, older, or more universally-supported symbology is specifically required, such as some industrial and ID-badge systems.

EAN-13 and UPC-A use the standard mod-10 algorithm — each of the 12 data digits is multiplied by an alternating weight of 1 and 3, and the check digit is whatever value makes the total a multiple of 10. Code 128 uses a weighted mod-103 checksum over each symbol's encoded value. Code 39 doesn't require a checksum at all (it's self-checking by design), but this tool offers an optional mod-43 check character for readers that expect one. All four are computed automatically — you never need to work them out by hand.

Yes — enter the 12 data digits for EAN-13 (or 11 for UPC-A) and the check digit is computed and appended automatically. If you enter the full 13 (or 12) digits instead, including your own check digit, the tool validates it and shows a clear error if it doesn't match what the standard checksum algorithm computes.

Each symbology only accepts certain input. Code 128 (Subset B) accepts any printable ASCII character; anything else — a tab, a newline, an emoji, most accented letters — is rejected with the specific invalid character named. Code 39 only accepts digits, uppercase letters, space, and - . $ / + % (lowercase is automatically uppercased, not rejected). EAN-13 and UPC-A only accept digits, in specific lengths, and reject a check digit that doesn't match what the standard algorithm computes for the rest of the number.

Yes — the bar patterns are built directly from each symbology's published encoding tables and checksum algorithms, the same specifications real scanner hardware and software implement, not an approximation. Print it at a reasonable size (very small prints can lose fine bar-width distinctions) with good contrast, and any standard barcode scanner or barcode-reading phone app should read it correctly.

No. Every symbology is encoded entirely in your browser from this tool's own logic — nothing you type is uploaded, logged, or sent to a server. The downloaded PNG or SVG is produced on an in-page canvas and saved directly from your browser to your device.