Vector Barcode Generator (Code 128 & UPC-A) | Print-Ready SVG & PNG

Industrial & Retail Barcode Symbology Standards

Linear (one-dimensional) barcodes encode data by varying the widths of parallel dark bars and light spaces. Governed globally by GS1 and the International Organization for Standardization (ISO), linear barcodes form the foundational backbone of retail inventory, international logistics, and automated point-of-sale checkout systems.

Linear Barcode Symbologies Reference Table

Symbology	Character Set	Check Digit Standard	Primary Commercial Usage
UPC-A	Exact 12 Digits (0-9)	Mandatory Modulo-10	US & Canadian retail consumer packaged goods
Code 128	Full ASCII (128 chars)	Mandatory Modulo-103	FedEx/UPS labels, supply chain, pallet distribution
EAN-13	Exact 13 Digits (0-9)	Mandatory Modulo-10	Global international retail outside North America
Code 39	43 Chars (A-Z, 0-9, -.$/+%)	Optional Modulo-43	US Department of Defense (MIL-STD-129), automotive parts

The GS1 Modulo-10 Check Digit Calculation Algorithm

To prevent point-of-sale scanner misreads, UPC-A barcodes append an algorithmic check digit in the 12th position:

Designate positions 1 through 11 from left to right.
Sum the values of all digits located at odd positions (1st, 3rd, 5th, 7th, 9th, 11th) and multiply this sum by 3: S_odd = 3 × ∑ D_odd.
Sum the values of all digits located at even positions (2nd, 4th, 6th, 8th, 10th): S_even = ∑ D_even.
Calculate total sum: T = S_odd + S_even.
The check digit is the amount required to round T up to the nearest multiple of 10: C = (10 - (T mod 10)) mod 10.

Frequently Asked Questions (US Standards)

How is the UPC-A Modulo 10 check digit calculated?

The UPC-A check digit is calculated using the official GS1 Modulo 10 algorithm across the first 11 digits: (1) Sum digits in odd positions (1st, 3rd, 5th, etc.) and multiply by 3. (2) Sum digits in even positions (2nd, 4th, 6th, etc.). (3) Add both sums together. (4) The check digit is the smallest number that makes the total divisible by 10 (or 0 if already divisible). Our generator computes this digit automatically if you input 11 digits.

What is the difference between Code 128 and UPC-A barcodes?

UPC-A is a fixed-length 12-digit numeric barcode mandated by GS1 US for retail point-of-sale scanning across North America. In contrast, Code 128 (ISO/IEC 15417) is a variable-length, high-density symbology capable of encoding all 128 ASCII characters, making it the global standard for shipping logistics, warehouse inventory, and packaging labels.

Why is SVG preferred over PNG for barcode printing?

SVG (Scalable Vector Graphics) defines barcode bars as mathematically pure vector rectangles rather than a raster grid of pixels. When printed on high-speed thermal transfer or laser label printers (such as Zebra or Dymo at 203 to 600 DPI), SVG eliminates anti-aliasing fuzziness and edge blurring, ensuring 100% first-pass scan readability.

Are my barcode serial numbers private?

Yes. Barcode generation, character encoding, and vector rendering execute 100% locally in your browser memory via pure JavaScript. No serial numbers, SKUs, or product payloads are transmitted to any external server.