What the calculator does
The calculator applies the GS1 modulo-10 algorithm to the data portion of a GTIN. It detects the intended GTIN format from the number of digits supplied, calculates the final digit and displays the complete number.
Example calculation
40063813339312 data digits → check digit 1 → complete GTIN-13: 4006381333931How the modulo-10 calculation works
Beginning at the rightmost data digit, alternating digits are multiplied by three and one. The products are added, and the check digit is the smallest value that makes the total a multiple of ten. The interface keeps this arithmetic secondary so the primary result remains easy to use.
Limitations
A mathematically correct check digit does not establish that the resulting number is licensed, assigned or suitable for a particular product. ProductPassKit does not issue identifiers.
Frequently asked questions
Should I include the existing check digit?
No. Enter only the data digits before the final check digit: 7, 11, 12 or 13 digits.
Does the calculator assign a GTIN?
No. It performs a mathematical calculation only. GTIN assignment and licensing are separate processes.