2D Barcode
Linear Barcode
UPC-A is linear barcode symbology of the EAN/UPC Symbology family. UPC is short for Universal Product Code which widely used for retailing industry to track Global Trade Item Numbers (GTIN) since 1970s. UPC-A was used to encode UPC-A encodes the EAN/UPC barcodes like GTIN-12, Coupon-12, RCN-12, and VMN-12. UPC-A is an subset of EAN-13. It usually composed of 12 numerical digits. Based on GS1 standards, UPC-A is the only barcode which could be used for scanning trade items in point of sale industry. The barcode shows details of the manufacturer and specific product. UPC-A is easy to be found on books, CDs and newspapers.
Structure of the UPC-A
The UPC-A barcode is composed of 4 parts, the number system to identify the type of the product, the manufacturer code uniquely assigned by UCC council, the product code and the checksum digit. The structure of UPC-A barcode showed as below represented as black bars and white spaces:
  • A left Quiet Zone. The number system digit is encoded to the left of the barcode
  • A normal Guard Bar Pattern
  • Six symbol characters from number set A
  • A centre Guard Bar Pattern
  • Six symbol characters from number set C
  • A normal Guard Bar Pattern
  • A right Quiet Zone. The checksum digit is encoded to the right side of the barcode.
In most of the cases, UPC-A barcodes encodes 12 numerical digits. These 12 digits are divided into 2 parts, each with 6 digits. The right-hand side of the first digit is positioned five module widths to the leftmost guard bar. Those numerical digits are assigned to the trade item. And A two-digit Add-On Symbol or five-digit Add-On Symbol may be used in an UPC-A barcode. Thus UPC-A supplement 2 (2-digit Add-on) or UPC-A suppliemnt 5 (5-digit Add-on) is obtained. The add-on digit symbol should be appended following the right Quiet Zone of UPC-A barcode.
Encoded Data of UPC-A
UPC-A encodes 11 digits of numeric numbers: 0~9

Plus the checksum digit, the total length is 12 digits long.
Checksum Digit of UPC-A
The checksum digit is essential to offer detection for scanning the barcode. Like EAN-13, the checksum digit is calculated based on the Mod10 standards. The Mod10 method is utilized for verification of barcode as: PC-A, UPC-E, EAN-13 and EAN-8.
Just follow the steps:
  • Choose the right most digits as the odd digit, and put it into the right most column below.
  • Assigned the following digits from right to left in sequence into the odd and even position.
  • Multiple all value in odd position with 3. Multiple all value in even position with 1.
  • Sum up all the result.
  • Put an number to add with the result and let it be even divided by 10.
  • The number added is the checksum digit. Like in the example, (8) +102=110. Number 8 helps number 102 to be even divided by 10. 8 is the checksum digit of the UPC-A barcode.
For example, the checksum digit is calculated as below if we encode "2345678912"

3+ 2 + 9 + 4 + 15 + 6 +21 +8 + 27 +1 + 6 = 102

We need to add No. 8 to 105, and it could be even divided by 10. (8)+102=110.

Note: If the result could be even divided by 10, like 100, the check digit is 0.

The checksum digit of "2345678912" is 8, the barcode ITF-14 generated is "23456789128"