Free UPC-A Barcode Generator

Understanding the UPC-A Structure

A UPC-A barcode contains exactly 12 digits, divided into four sections. The first digit is the Number System Character, which indicates the type of product: 0 is standard retail, 2 is variable-weight items (deli meat, produce), 3 is drugs and health products, 4 is in-store use, and 5 is coupons. Digits 2–6 are the manufacturer code assigned by GS1. Digits 7–11 are the item reference, chosen by the manufacturer. The 12th digit is the check digit, calculated using a modulo-10 algorithm from the first 11 digits.

GS1 company prefixes are required for products sold through major retailers. You cannot simply make up a UPC number — GS1 assigns unique prefixes to prevent barcode collisions across manufacturers. Contact GS1 US (gs1us.org) to obtain a valid prefix before printing UPC labels for retail distribution.

Minimum Size and Quiet Zone

The GS1 specification sets a nominal symbol height of 25.9 mm (1.02 inches) at 100% magnification. GS1 allows magnification between 80% (minimum) and 200% (maximum) for most applications. At 80%, the symbol is about 20.7 mm (0.82 inches) tall. Below this threshold, most retail point-of-sale scanners will fail to read reliably.

The quiet zone — the blank space on each side of the barcode — must be at least 3.63 mm (0.143 inches) wide on each side. Violating the quiet zone is one of the most common reasons a UPC-A fails to scan at checkout. When placing a UPC on packaging, keep that white space clear of text, images, and edges.

UPC-A vs. EAN-13

EAN-13 is the international equivalent of UPC-A. A UPC-A is technically an EAN-13 with a leading zero prepended, which means any scanner that reads EAN-13 can also read UPC-A. In international markets, EAN-13 is the standard. If you are selling globally, obtain an EAN-13 (or have your GS1 company prefix create one) rather than relying on UPC-A alone. Use our EAN-13 generator for international product barcodes.

Frequently Asked Questions