Obtain a GS1 Company Prefix
Assign a unique item reference to each product
Calculate the check digit using the UPC-A algorithm
Combine the number system digit, company prefix, item reference, and check digit
Format the result as a 12-digit UPC-A code
Use barcode generation software or a barcode library to convert the UPC number into a scannable barcode
Verify the barcode against UPC-A specifications
Test the barcode with a scanner before printing or use