How to Read UPC Barcodes

How to Read UPC Barcodes. Have you ever wondered what all those numbers and lines used to scan merchandise actually mean? Barcodes can be a bit frustrating and confusing if you don't know what you're looking at. These steps are designed to aid you in understanding the barcode how to read these labels.

Look at the barcode you want to read. It has black and white lines. Both of these are part of the code and vary in thickness. For the black lines there are four different thicknesses.

Examine the beginning of the barcode. You can see that every barcode begins with a skinny black line followed by a white one and another black one.

Move to the center of the barcode. Here you will notice that a series of five of the skinniest order of lines is present. Every barcode has this in the middle. There are also two black lines in the center that extend down in between the actual digits.

Notice that each of the digits at the bottom of the code has its own unique four line arrangement.

Assign number values to the differing lines. Using 1, 2, 3, and 4 works best. If the barcodes digits at the bottom begin with a 3 and the lines are, in order, 3 followed by 2, 3, 1 the barcode actually says 33231 in that section.

Turn your attention to the actual digits printed under the lines of the barcode. To the far left is a slightly smaller digit. This indicates the variety of barcode. For example a 3 would indicate a coupon.

Move on to the first set of five digits directly under the lines. These digits indicate the manufacturer of the product. Every manufacturer has a unique digit sequence that appears on all their products.

Look at the second set of five digits. These are the product identification numbers. Every different product has its own set of digits. For example a bag of chips has its own set and a slightly smaller bag of the same brand has a different set. But all bags of the original size will carry the first set.

Focus on the final digit to the right of the lines. This number tells the machine that is scanning if it has done its job correctly. The scanner sends the digit to the store's main computer. This computer sends back the actual barcode and it checks against itself to make sure the pricing and item identification is correct.


  • It is going to take a lot of practice before you can remember the different thicknesses of the lines. Keep at it. You can scan the item you are trying to read to check your work when you are reading these labels.


  • Barcodes are not the same outside the United States. You will have to learn a whole new set of codes for other countries.

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