Damm Algorithm Check Digit Tool

This page is meant as a very basic tool to aid users of the Damm check digit algorithm. I created this for my own uses but hope that it may be helpful for someone else too! This tool uses only client-side javascript which can be reviewed by looking at the page source.

Calculate Damm Check Digit

Enter a number into the box and the check digit will be appended below. Note non-digits will be ignored but left in place.

Enter Number To Calculate

Verify Damm Check Digit

Enter a number to test the last digit as a Damm check digit. Text below the box will display if the number is valid or invalid. Note non-digits will be ignored but left in place.

Enter Number To Verify

3 replies on “Damm Algorithm Check Digit Tool”

Nice tool! Would be helpful if it would automatically strip out invalid characters (like hyphens) before calculating the check digit.

Good idea, I will add it to my to-do list. Do you think all invalid characters should be removed and then remaining numbers behave as one large number or something else such as discarding all characters after an invalid one? I think the first way makes most sense.

I have implemented a change that just ignores the invalid characters but leaves them in place. Let me know if you find any bugs

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