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ORCID Validator

Paste an ORCID iD to check whether its check digit is valid.

How it is calculated

The tool removes every character except digits and the letter X (so hyphens, spaces and a leading https://orcid.org/ are ignored, and lower-case x is accepted), and then requires exactly 16 characters. For the first 15 digits it keeps a running total: total = (total + digit) × 2. The check character is (12 - total mod 11) mod 11, written as X when the value is 10. The result is "Valid" if this matches the 16th character, otherwise "Invalid", and the computed check character is shown with the number reformatted in four groups of four. This only tests that the number is well-formed. It cannot tell whether the iD has been issued to anyone or whose it is. A wrong length or an X anywhere except the end gives no result at all.

Worked example

Check 0000-0002-1825-0097. The first 15 digits are 000000021825009. Seven zeros keep the total at 0. Then: (0 + 2) × 2 = 4; (4 + 1) × 2 = 10; (10 + 8) × 2 = 36; (36 + 2) × 2 = 76; (76 + 5) × 2 = 162; then two zeros give 324 and 648; finally (648 + 9) × 2 = 1314. Now 1314 mod 11 = 5 and (12 - 5) mod 11 = 7. The last digit of the iD is 7, so the tool reports Valid.

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Common mistakes

  • Assuming "Valid" means the researcher exists; the check only proves the digits are internally consistent, and an iD that was never issued can still pass.
  • Typing the letter O instead of the digit 0, or l instead of 1; those letters are dropped, the length is no longer 16 and no result appears.
  • Mistaking a trailing X for a typo: X is a legitimate check character that stands for the value 10, as in 0000-0002-9079-593X.
  • Pasting a whole sentence or a URL that contains other digits (such as a year or a path number); every digit found is read as part of the iD.
  • Expecting the tool to find which digit is wrong; a mismatch shows only the check character it expected, and the typo may be in any position.

About this calculator

An ORCID iD is a free, persistent 16-digit identifier (formatted as four groups of four digits, e.g. 0000-0002-1825-0097) that uniquely distinguishes a researcher from everyone else who shares their name. The final character is a check digit computed with the ISO 7064 MOD 11-2 checksum: each preceding digit is added to a running total which is then doubled, and after processing all 15 digits the check value is (12 − total mod 11) mod 11, displayed as the digit itself or as “X” when the result is 10.

Publishers, funders, and university repositories validate this check digit before linking an ORCID iD to a manuscript, grant, or profile, since a single mistyped digit would otherwise misattribute someone’s publication record. Crossref requires a valid ORCID for author disambiguation on many journal submissions, and institutional CRIS systems run the same MOD 11-2 check on data entry — this calculator reproduces that exact validation so you can confirm an iD is well-formed before using it.

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Comments (1)

  • Editorial team

    A Valid answer only says the final check character fits the first fifteen digits (ISO 7064 MOD 11-2, where the last character can be X). It does not prove the number was ever issued to a researcher, and a mistyped digit can occasionally still pass. For anything formal, open the ID in the ORCID registry. Where did your identifier come from: a paper, a form, a CV?

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