How do I calculate a ITF14 code for the outside of a carton from the
UPC code 0-24327-31995-9?

mapman1-ga:

Calculating an ITF-14 code for a given UPC-12 code involves prepending
a zero in order to make it an EAN-13 code, dropping the check code
(the last digit), prepending a carton size digit (assigned by the
manufacturer), then calculating a new check code as the new last
digit.

In the case of UPC: 0 24327 31995 9
The EAN-13 code is: 0024327319959

Using '1' as the carton size digit, the ITF-14 code is therefore:
10024327319956


The algorithm for converting UPC-12 numbers to an ITF-14 number is
explained in greater detail at the following Singapore Article
Numbering Council website:

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"Understanding EAN Code"

http://www.nepc.sanc.org.sg/html/DataDictionary/EANCode.htm


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I hope this helps.

Regards,

aht-ga