How to use the iso 7064 check character calculator
- Pick the system: MOD 11-2, 37-2, 97-10, 11,10, 27,26 or 37,36.
- Choose whether to find the check or to test a number.
- Enter the number. Spaces and hyphens are ignored. To find the check, leave the check characters off. To test, include them at the end.
- Read the check character, the complete number or the verdict, with the details in the table.
Formula
pure system (MOD 11-2, 37-2): total = (total x 2 + value) mod M for each character; check = (1 - 2 x total) mod M
MOD 97-10: put two zeros after the number, take the remainder mod 97; check digits = 98 - remainder
hybrid system (MOD 11,10; 27,26; 37,36): p = M; for each character s = (p + value) mod M (0 becomes M), p = 2s mod (M + 1); check = (M + 1 - p) mod M
a number with its check passes when the final total is 1 (pure) or the last s is 1 (hybrid), or the remainder mod 97 is 1
M is the number of characters in the set: 11 for MOD 11-2 (digits and X), 37 for MOD 37-2 (digits, letters and a star), 10, 26 or 36 for the hybrid systems.
Three published uses
An ORCID iD is 15 digits plus a MOD 11-2 check. For 0000-0002-1825-009 the check is 7, giving 0000-0002-1825-0097. For 0000-0001-5109-370 the check is 0, and for 0000-0002-1694-233 it is the letter X, which stands for 10.
Under MOD 97-10, the IBAN GB82 WEST 1234 5698 7654 32 is checked by moving the first four characters to the end, reading letters as 10 to 35, and finding a remainder of 1 modulo 97. The tool finds 82 as the check digits of WEST12345698765432GB. For a number checked with ISO 7064 MOD 11,10, the ten digits 6592997048 have the check 9, giving 65929970489.
Pure and hybrid systems
In a pure system one arithmetic rule, such as weighted sums, is applied to the whole number. In a hybrid system, the arithmetic uses two nearby moduli, which lets the check character come from the same alphabet as the data and catches every single character mistake and every swap of neighboring characters. The tool names each system as the standard does.
For other check digits, such as Luhn, ISBN or EAN, use the Check Digit Validator. The ORCID and ISNI Checksum Validator is a shortcut for those identifiers, and the Non-Cryptographic Hash Calculator covers fast hashes of longer data. For a file checksum, use the CRC32 Checksum Calculator.
What a pass does and does not show
A check catches typing mistakes. It cannot show that a number was issued to anyone, and anyone can compute a valid-looking number. Each scheme that uses these systems adds its own length rules, prefixes and character sets, and those are not checked here.
Assumptions and limits
- Digits are 0 to 9, letters are A to Z in the order of the alphabet, and for MOD 37-2 the star is the 37th character.
- In MOD 27,26 the letters A to Z are the values 0 to 25, and in MOD 37,36 the digits come first and then the letters.
- MOD 97-10 uses the check digit rule of IBANs, so the check digits run from 02 to 98.
- Up to 40 characters are read, and nothing is uploaded.
Frequently asked questions
Does ISO 7064 define one algorithm?
It defines a family. Each system has its own size, alphabet and rule, and each real scheme picks one. That is why the tool asks you to choose a system before it reads the number.
Why can a check digit be X?
MOD 11-2 has eleven possible check values, 0 to 10, and ten does not fit in one digit. By convention it is written as the letter X.
What does it mean when MOD 11,10 is called hybrid?
It combines two moduli, 10 and 11, in one calculation. This makes the check digit one ordinary digit while still detecting all single errors and swaps of two neighboring digits.
Is a valid check enough to trust an IBAN?
No. It shows the characters are consistent with each other, which catches most typing slips, but the account must still exist, and each country adds length and format rules not checked here.