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Structure of the ORCID Identifier

Format of the ORCID iD

The ORCID iD is an https URI with a 16-digit number that is compatible with the ISO Standard (ISO 27729), also known as the International Standard Name Identifier (ISNI), e.g.

Initially ORCID iDs will be randomly assigned by the ORCID Registry from a block of numbers that will not conflict with ISNI-formatted numbers assigned in other ways. ORCID iDs always require all 16 digits of the identifier; they can not be shortened to remove leading zeros if they exist.

No information about a person is encoded in the ORCID iD. The identifiers were designed to be usable in situations where personally-identifiable information should/can not be shared. Also, since the ORCID iD is designed to be a career-long identifier, no information that can change over a person's career is embedded in the iD, e.g., country, institution, field of study.


The last character in the ORCID iD is a checksum. In accordance with ISO/IEC 7064:2003, MOD 11-2, this checksum must be "0" - "9" or "X", a capital letter X which represents the value 10. View the algorithm used below to determine the checksum of an ORCID iD, or see it in action using the ORCID Checksum Digit tool.

  * Generates check digit as per ISO 7064 11,2. 
public static String generateCheckDigit(String baseDigits) { 
    int total = 0; 
    for (int i = 0; i < baseDigits.length(); i++) { 
        int digit = Character.getNumericValue(baseDigits.charAt(i)); 
        total = (total + digit) * 2; 
    int remainder = total % 11; 
    int result = (12 - remainder) % 11; 
    return result == 10 ? "X" : String.valueOf(result); 

Issuing ORCID iDs

Only the ORCID Registry can assign ORCID iDs. ORCID iDs are intended to be assigned to individuals and may be secured at no charge. ORCID iDs will be assigned randomly from a block of numbers reserved for this purpose. Typically, the 16-digit identifiers are assigned between 0000-0001-5000-0007 and 0000-0003-5000-0001.

Expressing the ORCID iD

The ORCID iD is expressed as an https URI, i.e. the 16-digit identifier is preceded by "". A hyphen is inserted every 4 digits of the identifier to aid readability. 

Storage of the ORCID iD in a database

When stored, the ORCID iD should be expressed as a full https URI:, complete with the protocol (https://), and with hyphens in the identifier (xxxx-xxxx-xxxx-xxxx). 

Display of the ORCID iD 

ORCID's current recommended display is a full https URI preceded by the iD icon, both hyperlinked to the https URI:

At a minimum, the ORCID iD should be displayed as the full https URI. For more, see the ORCID trademark and iD display guidelines

Expression of the ORCID iD in the ORCID XSD Schema





Some sample ORCID iDs

Below are some example ORCID iDs with checksums as described above and expressed in the proper format.

      Related resources

      Learn about how the structure for the ORCID Identifier was chosen: Structure of ORCID Identifiers Whitepaper by Geoffry Bilder.

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