How to use the orcid and isni checksum validator
- Type or paste the identifiers, one on each line. Hyphens, spaces and a leading https://orcid.org/ are removed for you.
- Use 16 characters to test an identifier, or 15 digits to have the last character worked out.
- Read the result for each line: whether the check character works, and which character would be needed if it does not.
- Copy the link form or the spaced ISNI form from the table for the identifiers that pass, or download the CSV.
Formula
total = 0
for each of the first 15 digits: total = (total + digit) x 2
check value = (12 - total mod 11) mod 11, where 10 is written as X
This is the ISO 7064 MOD 11-2 method. It gives a check character from 0 to 9 or X, and it detects every single wrong digit and every swap of two neighboring digits.
Checking 0000-0002-1825-0097
The first 15 digits are 000000021825009. Processing them in turn, the total stays 0 for the seven leading zeros, then becomes 4 after the 2, 10 after the 1, 36 after the 8, 76 after the 2, 162 after the 5, 324 after the 0, 648 after the next 0 and 1,314 after the 9.
Dividing 1,314 by 11 leaves a remainder of 5, and 12 minus 5 is 7. The expected last character is 7, which matches. Swap the last two digits to 0079 and the page reports that the check character fails and that the last character would be 7.
ORCID and ISNI share one rule
An ORCID identifier is a 16 character number for a researcher, written in four groups of four, such as 0000-0002-1825-0097. An International Standard Name Identifier (ISNI) is also 16 characters and uses the same check method. The only difference on this page is how they are written: ORCID with hyphens or as a link, ISNI with spaces.
The last character can be the letter X, which stands for a check value of 10, so a valid identifier can end in a letter.
What passing does not show
A passing identifier is consistent. It does not show that the number was ever issued or who it belongs to, and it gives no information about a person. Look an identifier up with the organization that issues it when you need to know that it is real.
For other numbers with check digits, try the Check Digit Validator. For health records see the NHS Number Check Digit Validator.
Assumptions and limits
- Only the arithmetic of the 16 characters is tested. The page makes no lookups.
- The identifier must have 15 digits followed by one digit or the letter X, with hyphens, spaces and an orcid.org link prefix ignored.
- The link form shown always uses https://orcid.org/ and the hyphenated number.
- Up to 200 lines are read at once.
- Nothing typed here leaves your browser.
Frequently asked questions
Can an ORCID end in a letter?
Yes. When the check value is 10 it is written as the capital letter X. A lowercase x is accepted when you type it and shown in capitals.
Are all passing numbers real researcher identifiers?
No. Roughly one in eleven random 16 character strings would pass by chance. Whether a number has been issued is recorded by the registry, which this page does not contact.
Why do hyphens not matter?
Hyphens only group the digits for reading. The check is calculated on the 16 characters without them, so the page removes hyphens, spaces and a web address prefix before testing.
How is the total built up digit by digit?
Each step adds the next digit to the running total and then doubles it. After 15 digits the first digit has been doubled 15 times and the last one once, which is why the earliest digits weigh the most.