Caution: All characters in the GMN are case sensitive
*(for GMN validation only)
Caution: All characters in the GMN are case sensitive
Button definitions
Calculate > Calculate your check character pair from your GMN (Basic UDI-DI) without check characters.
Validate > Perform checks on the complete GMN (Basic UDI-DI) including check characters.
Structure of the Basic UDI-DI (GMN)
The last two characters of the basic UDI-DI are check characters calculated on the previous characters used. The calculator is specifically for a maximum of 25 characters including the check character pair for the Basic UDI-DI. Use our check character calculator above to calculate the check character pair.
What is a check character?
The check character pair are two uppercase alpha and numeric characters used to detect potential character keying and encoding errors. The GMN (Basic UDI-DI) has a mandatory check character pair.
How does the GMN generator work?
The check character calculator uses an algorithm, based on other numbers and characters in the GMN. See how the check characters are calculated. You can also refer to our GMN helper libraries for support.
Find out more
GS1 US
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