Online Code-128 Barcode Generator

Code-128 is a high-density linear barcode symbology that can encode all 128 ASCII characters. It is widely used in logistics, inventory management, shipping labels, and healthcare. Its compact design and ability to encode alphanumeric data efficiently make it one of the most popular barcode formats worldwide. Code-128 uses a checksum for error detection and supports three encoding subsets: A, B, and C.

Code-128A encodes uppercase letters (A-Z), digits (0-9), control characters (ASCII 0-31), and special characters.
Code-128B encodes uppercase and lowercase letters (A-Z, a-z), digits (0-9), and all printable ASCII characters (32-127). This is the most commonly used subset.
Code-128C encodes numeric data only, packing two digits into each symbol — ideal for long numeric strings like UPC codes or serial numbers, reducing barcode length by ~50%.

Our Auto mode intelligently scans your input and selects the optimal encoding strategy. For numeric sequences of 4+ digits, it switches to Code-C for compression. For mixed alphanumeric text, it defaults to Code-B. It can even insert mode-switch symbols mid-barcode to minimize overall length, giving you the most compact barcode possible.

Code-128 includes a modulo-103 checksum for error detection. It is calculated as: (start_code_value + Σ(position × symbol_value)) mod 103. The checksum symbol is appended before the stop character. This ensures that scanning errors are caught reliably — if the checksum doesn't match, the scanner rejects the read.

Code-128 only supports standard ASCII characters (0-127). Extended Unicode characters (é, ñ, ç, emoji, etc.) cannot be directly encoded. If you need to encode non-ASCII data, consider using a 2D barcode like QR Code or Data Matrix instead. For European characters, you may use ASCII transliteration or UTF-8 encoded as hex in Code-128 (though this is non-standard).

There is no strict maximum length defined in the Code-128 standard, but practical limits apply. Most barcode scanners can read up to 60-80 characters comfortably. Longer barcodes become wider and may not fit on labels or scan reliably. For very long data (100+ characters), consider splitting into multiple barcodes or using a 2D symbology like QR Code.

Most modern barcode scanners (laser, CCD, and camera-based) support Code-128 natively. You can also use smartphone apps like ZXing Barcode Scanner, Scandit, or built-in camera apps on some devices. Simply point the scanner at the barcode — Code-128's high contrast and checksum make it very reliable even on curved or slightly damaged surfaces.

Code-128: Highest density, encodes full ASCII, best for alphanumeric data and logistics.
Code-39: Older standard, only A-Z and 0-9 plus a few symbols, lower density, but very widely supported.
EAN-13: Fixed 13-digit numeric only, used for retail products with GTIN numbers.
Choose Code-128 for flexibility and compactness; Code-39 for legacy systems; EAN-13 for retail point-of-sale.

Yes! Download the barcode as PNG (raster, suitable for most uses) or SVG (vector, infinitely scalable for print). For professional printing, we recommend SVG format at 300+ DPI. Ensure adequate quiet zone (blank margin) on both sides — our generator includes configurable quiet zones. For label printers (Zebra, Dymo, etc.), the PNG at 203 DPI works well.