Canadian · Validation
ISSN check digit validator.
Verify an ISSN (International Standard Serial Number, the eight-character identifier for journals, magazines and other serials, written NNNN-NNNC), or enter just the first 7 digits to have the check character computed. Everything runs in your browser: nothing you type is transmitted anywhere.
Inputs
Result
Enter an ISSN and press Validate.
How the ISSN check character works
An ISSN is two groups of four digits separated by a hyphen. The eighth character is a check character calculated with a modulus 11 algorithm from the seven digits before it, and it is an X when the result is 10 (ISSN International Centre; ISO 3297).
Multiply the first seven digits by 8, 7, 6, 5, 4, 3 and 2 and add the products. Take the sum modulo 11: if the remainder is 0 the check character is 0, otherwise it is 11 minus the remainder, and a result of 10 is written X.
Worked example, 0378-5955 (Hearing Research): 0×8 + 3×7 + 7×6 + 8×5 + 5×4 + 9×3 + 5×2 = 160; 160 mod 11 = 6; 11 − 6 = 5, so the ISSN is valid. The ISSN Centre’s own examples 0317-8471 and 1050-124X (an X check character) also validate.
What a passing checksum does and doesn’t tell you
A valid check digit only proves the digits are internally consistent — it does not confirm the number was ever assigned to a real publication by an ISSN National Centre. This tool runs entirely in your browser: nothing you type is transmitted, stored, or logged.