ISSN Validator
ValidatorValidate ISSN periodical serial numbers. Checks the 8-character format and recomputes the official check character. Runs entirely in your browser.
About this tool
About ISSN Validator
An ISSN (International Standard Serial Number) is an 8-digit code, written as 1234-5678, that uniquely identifies a periodical publication — a journal, magazine, or newspaper — independent of its title, which can change over time. This validator confirms the format and recomputes the check character to verify the code is internally consistent.
The validator strips whitespace and the hyphen, verifies the 8-character format (7 digits followed by a digit or the letter X), multiplies each of the first 7 digits by weights 8 through 2, sums the results, and compares the computed check character — including the special case where a remainder of 10 becomes the letter X — against the 8th character.
Use this to verify an ISSN printed on a journal, magazine masthead, or library catalog record before using it in a citation manager or library system, to debug why an ISSN is being rejected by a validation layer, or to sanity-check an ISSN pasted from a publisher's website.
Instant, fully client-side validation with no data ever leaving your browser. Note this checks structural validity only — it does not confirm the ISSN is actually registered to a real publication, which requires a lookup against the ISSN International Centre's register.
Key Features
- Full 8-character format validation
- Handles the special 'X' check character case
- Recomputes and compares the official check character
- Clear error messages for each failure mode
- Verified against real published ISSNs
- 100% browser-based, no data ever transmitted
FAQ
ISSN Validator — Frequently Asked Questions
What is an ISSN?
ISSN stands for International Standard Serial Number, an 8-digit code that uniquely identifies a periodical publication — a journal, magazine, or newspaper. Unlike an ISBN, which identifies a specific book, an ISSN identifies the ongoing publication itself, independent of any single issue.
How is the ISSN check character calculated?
Multiply each of the first 7 digits by weights 8, 7, 6, 5, 4, 3, and 2 respectively, sum the products, and take the result mod 11. The check character is 11 minus that remainder — except when the result would be 10, in which case the check character is the letter X.
Why does an ISSN sometimes end in the letter X?
Because the check digit calculation can produce a result of 10, which isn't a single digit. Following the same convention as ISBN-10, the letter X is used to represent that value instead.
What's the difference between an ISSN and an ISBN?
An ISSN identifies a periodical — a journal, magazine, or newspaper that continues publishing new issues over time. An ISBN identifies a specific book or a specific edition of a book. Some publications, like an annual conference proceedings, may have both.
Why does my ISSN fail validation?
The most common cause is a single mistyped or transposed digit. Also confirm the code is exactly 8 characters (7 digits plus a check digit or X), with or without the hyphen.
Tips
- Strip the hyphen before validating if your source formats the ISSN as 1234-5678 — this tool accepts it either way
- If the check character fails, try re-copying the ISSN from its original source — the most common error is a single transposed digit
- A trailing X is not an error — it's the standard way to represent a check value of 10
- This validator never sends your ISSN anywhere — the check character is recomputed entirely in your browser
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