When you calculate a check digit for GTIN-12, or GTIN-13, the GS1 number will consist of 12 and 13 digits respectively. If the number is to be saved in a database or used in a GS1-128 or a GS1 DataMatrix, you need to make the number 14 digits long by filling in the digit 0 in front of the number. The leading zero should not be included in the barcode EAN-13.
Please note that the GS1 numbers you calculate here are neither saved nor registered.
To calculate the check digit for one number, type 1 in the field “Ammount of numbers”, or use the calculator on GS1’s Global website, where you also can calculate the check digit for other GS1 keys.