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Guide to UPC Codes

About Universal Product Code (UPC) Barcodes

Most consumers are familiar with the barcodes on items that are scanned in grocery stores as well as seen on just about any type of manufactured product, from small glass vials to steel beams. That specific type of barcode is the Universal Product Code or UPC. UPCs have been in retail use since 1974. Today, the UPCs of an average of 5 billion products are scanned daily.


There are a few types of UPC barcodes, but the UPC-A is used for most U.S. retail, and is a unique 12 digit identification number for an individual product. (For very small items on which the standard UPC-A barcode will not fit, the smaller UPC-E barcode might be used, which contains only 6 digits.)


Although a UPC is not legally required, each industry dictates its own requirements. In the industrial and scientific marketplace, these codes are typically used for product identification, storage rack locations, and product identification. In general, all products sold at the retail level require a UPC. It is also becoming the standard for most Business to Business transactions.


When a UPC is required, high standards are strictly enforced. In some cases, a non-readable UPC can cost product owners fines at the retail level. Incorrect inventory receipt can cost thousands of dollars in unpaid invoices or lost product. Therefore, it is important to understand what is involved in the creation of a quality, readable UPC.



Understanding UPC-A Barcodes

  • Number System Character: the first number of the UPC, this number assigned by the Uniform Code Council simply indicates the number system that is to follow. Different types of products have different number system characters. For example, “2” is for random-weight items like meat, and “3” is usually used for pharmaceuticals.
  • Manufacturer Identification Number: a unique 5 digit number assigned by the Uniform Code Council.
  • Item Number: a 5 digit number assigned and controlled by the product owner.
  • Check Character: Also known as the “check digit”, this is last number of the UPC, and its purpose is to verify the accuracy of the entire UPC.




Important UPC Features

  • Bar/Space Pattern: every number has a unique pattern of bars and spaces of varying widths. Accurate printing of these patterns and their widths is essential.
  • Quiet Zone: There is a required area to the left and right of the barcode that must be free of all printing, and this is known as the “Quiet Zone”. The quiet zone prepares the scanner for the barcode that is to follow. Quiet zones are required on both ends so that barcodes can be read from either direction.
  • Size: For UPC-A, the nominal size is 1.469 inches wide by 1.02 inches high, including the number system and check characters. The maximum recommended size, 200% of the nominal size, is 2.938" w x 2.04" h. The minimum recommended size is 80% of the nominal size, or 1.175" w x .816" h. Size may vary depending on package design and printing conditions. In general, larger UPC's scan better.
  • Contrast: The level of contrast between bars and spaces helps determine the readability of a barcode. Although many color combinations may be used, the most reliable and common combination is black bars with white spaces. If black/white is not feasible, an alternative combination of dark bars with light spaces is always recommended. Since the barcode scanner uses infrared light to read the barcode, the color red cannot be scanned and therefore should never be used in a UPC.


Tips for Readable UPC’s

  • Printing Methods: Different printing methods affect the image quality of a UPC in different ways and, therefore, steps must be taken to counteract any negative effects. For example, in silk screening, the occurrence of ink spread must be calculated and bar width reduction must be incorporated into the film master. Ink spread can also decrease the flexibility of size reduction of a barcode. If a barcode is reduced too much, an attempt to silk screen it will blur the bars together. This is one of the reasons why it is recommended to keep the barcode within the minimum of 80% of the nominal size.
  • Positioning: The printing methods also affect the position of the barcode. With any method that might involve ink spread, it is best to position the barcode on its side so that the bars run in the same direction as the ink flows during the printing process. This insures that any blurring will affect bar length rather than bar width, because bar length is more important for readability.
  • Location: It is best to have the UPC barcode located so that it will be easy to find and scan. Generally, the UPC should be located in the center of the package's "natural bottom". This is determined by considering the physical design of the container as and the graphic design of the packaging. Many industries have their own specific criteria for UPC barcode placement.
  • Show-Through: Show-through can occur with transparent or translucent packages when the product is seen through the spaces of a barcode. If show-through occurs, the barcode may not be readable. For translucent packaging, it is recommended to opaque white background with dark bars for the barcode.
  • Truncation: Truncation means decreasing the height (but not the width) of a barcode. Truncation is not recommended (although ocassionally necessary), because it may decrease scannability. Instead, should try to reduce the barcode size within the existing ratio of height to width.


Your Account Executive can help you with any questions you might have about the UPC. Many Qorpak products carry barcodes specific to their distribution partners’ requirements. Our capabilities include bar coding of individual products, packs, bags, and cartons. You can also contact the GS1 (formerly known as the Uniform Code Council) for general characteristic questions.