There are a couple exceptions described immediately below this step, in which you can find partial information. GTIN refers to the data system UPC is a part of, short for Global Trade Item Number. [1] X Research source 12 digit UPC numbers can be referred to as GTIN-12, UPC-A, or UPC-E.

For example, a company might be assigned the code 123456. It can then print any 12-digit barcode that begins 123456, creating one for each product. Compare two barcodes from the same company to see whether you can figure out what the company code is. The purpose of the final digit is explained later on in this section.

This type of 12-digit number is sometimes referred to as a UPN, or Universal Product Number. [3] X Research source Although drug codes are always 10 digits long, they may also include hyphens (or spaces), which are not shown in the barcode. For example, 12345—678—90 and 1234—567—890 are different drug codes, but only one of them can use the same sequence of numbers as a barcode.

Type the entire barcode into GSI’s company lookup, in the “GTIN” field, to find the manufacturer. This will also show you which part of the barcode is the company prefix (typically the first six digits, but not always). The remaining digits (except for the very last one) should be the code used to denote weight or price.

Add all the digits in the odd positions together (the 1st, 3rd, 5th, 7th, 9th, and 11th digits). Multiply the result by 3. Add to this the sum of the even-positioned digits (the 2nd, 4th, 6th, 8th, and 10th) - do not include the check digit itself. “Chop off” everything except the final digit of your answer, the number in the ones place. If that number is 0, that is the check digit. If that number is any other digit, subtract it from 10, and the result is the check digit. For example, if the previous step resulted in an answer of 8, you would calculate 10-8=2. This answer should be the same as the final 12th digit of the barcode.

Barcodes using non-UPC systems or different numbers of digits cannot be read using this method. Most barcodes on products sold in the U. S. and Canada are UPC barcodes, but be wary of compressed 6-digit UPC barcodes, which have a different, more complex encoding system.

Don’t confuse this for the actual numbers you’re trying to find, the numbers 1 through 4 only describe the width of the bars.

For example, if the first white bar after the extra-long lines on the left hand side is the thinnest size, write down 1. Next, if the black bar to the right is the thickest size, write down 4. Once you’ve done this for four bars (black and white), leave a space before writing down the next bar. For example, once you’ve written down “1422,” move your pen to a new line before writing down the next bar width.

3211 = 0 2221 = 1 2122 = 2 1411 = 3 1132 = 4 1231 = 5 1114 = 6 1312 = 7 1213 = 8 3112 = 9