Bar codes are machine-readable data used to facilitate inventory tracking of products and uploading of information into various computer programs. Bar codes are created with the use of bar code-generating software, and are printed using either an ordinary or a bar code printer to produce bar code stickers. Bar codes can be changed anytime by encoding the new data, printing a new bar code sticker, and placing the sticker over the old bar code.

Things You Will Need
  • Bar code-generating software

  • Bar code scanner

Open your Internet browser and visit websites that offer free use of bar code-generating programs such as, or (see Resources).

View the program interface typically presented on the website's home page. Look at the list of bar code types and click on "UPC" or "UPC-A." Enter new data that you wish to encode in the space provided, and click on "Generate Barcode" to generate the bar code image. See the generated bar code image.

Right-click on the bar code image, and click "Save Image As" to save the bar code image on your computer. Select a location on your hard drive where you want to save the bar code image, and click "Save."

Right-click the saved image, and click "Print" in the resulting pop-up menu to print the bar code image. Select the page layout and paper size in the next window and follow onscreen instructions to to finish printing. Scan the bar code using a bar code scanner and check your computer to see if the uploaded data is correct. Cut out the printed bar code image and glue or stick it neatly over the old bar code.