UPC-A Barcode Symbology Overview
UPC-A barcode character set, checksum and structure & recommended barcode library for ASP.NET, Winforms, Word and Excel
UPC-A Barcode Introduction
The barcodes utilized by GS1 include EAN/UPC, GS1 DataBar, GS1-128, ITF-14, GS1 DataMatrix, and Composite Component. A trade item that is intended to cross the Point-of-Sale in a retail outlet must carry a bar code symbol, allowable symbols are EAN-13 and UPC-A.
UPC-A was used to encode GTIN-12, Coupon-12, RCN-12, and VMN-12. UPC-A is an subset of EAN-13 and is widely used on books, CDs and newspapers. Each UPC-A encodes 11 digits into a symbol and addpended with checksum digit which makes the total length to be 12 digits long. UPC-A uses a two/five-digit Add-On Symbol to encode information supplementary to that in the main barcode symbol.
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Detailed Information for UPC-A and UPC-A Supplementary Barcodes
UPC-A Structure
The UPC-A barcode symbology should compose of 4 parts, among which are number system to identify the product type, the manufacturer code uniquely assigned by UCC council, the product code encoded in UPC-A and the checksum digit. UPC-A barcode symbology is represented as black bars and white spaces. When supplemental digits considered, it should be appended following the right Quiet Zone of UPC-A barcode symbology.
- A start Quiet Zone
- 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 trailing Quiet Zone
Modulo 10 checksum digit
Like barcode EAN-8, UPC-A utilizes the modulo 10 calculation formula to compute the check digit. It is essential to employ the checksum digit since it offer detection for scanning the barcode. It is easy to compute checksum digit of UPC-A, just follow the steps:
- Find the right most digit of UPC-A and assigned it in the Odd position.
- Put the other digits from right to left and it should follow the sequence of Odd-Even-Odd position until the left end.
- Assign those digits in Odd position with weighting 3, and assign digits in Even position with weighting 1.
- Multiple the assigned weighting value with digit value.
- Sum up all the results and divide it with 10.
- Add a number plus the result. The summary could be evenly divided by 10. The number added is the checksum digit. And if the results could be evenly divided by 10, the checksum digit is 0.
For example, the check digit of "15896324895 " is 0.