ISIN validate

Client

International Securities Identification Numbers label instruments for settlement and reference data. This page confirms the ISO 6166 pattern—two-letter country, nine-character national security identifier, and decimal check—then recomputes the Luhn step on the digit expansion of the first eleven characters.

What is checked

Non-alphanumeric separators are removed and the value must be exactly twelve characters. The check digit must be a decimal digit; the preceding nine-character NSIN may contain uppercase letters or digits. Letters in the first eleven positions expand to two-digit numbers before applying the same Luhn mod 10 chain used for payment identifiers, but with the ISO 6166 expansion rules—not the CMS NPI prefix.

Related tools

For book identifiers, use ISBN validate. For plain digit Luhn chains, use Luhn checksum.

Privacy: validation runs only in your browser. This is not a trading or issuer lookup—only ISO layout and the check digit. Treat live identifiers carefully on shared machines.
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Spaces and hyphens are removed. A valid code is 12 characters: ISO country (two letters), nine-character NSIN (letters A–Z or digits), and one decimal check digit. The check uses Luhn mod 10 over the digit string obtained by expanding letters to two-digit values (A=10 … Z=35), per ISO 6166.

Result

Passes ISO 6166 check digit.

Normalized: US0378331005

Country
US
NSIN (9)
037833100
Check digit
5

Common use cases

  • Verify a ticker-adjacent identifier from a CSV export before loading it into an internal reference master.
  • Sanity-check an ISIN copied from a factsheet when wire instructions also list a separate CUSIP or SEDOL.
  • Contrast ISO 6166's Luhn step with the unrelated ISBN-10/ISBN-13 rules when onboarding adjacent teams.
  • Pair with the generic Luhn tool when explaining that ISIN expands letters before the mod-10 pass.

Common mistakes to avoid

  • Confusing ISIN with ISBN

    ISBN identifies books with different checksum rules; this page expects twelve-character securities identifiers only.

  • Treating a passing check as proof of listing or liquidity

    Only structure and check digit are validated here—trading status, issuer data, and corporate actions live elsewhere.

  • Expecting country letters to prove domicile

    The prefix follows ISO rules for the code, but interpretation of the NSIN still depends on national numbering agencies.

FAQ

Is my ISIN uploaded?

No. Parsing and the check digit run entirely in your browser tab like other client-side validators on Toolcore.

Do you fetch prices or issuer facts?

No—there is no market data or registry call; use your broker or data vendor for fundamentals.

How does the check digit work?

The first eleven characters are expanded to digits (each letter becomes two digits, A=10 through Z=35), then the Luhn mod 10 algorithm is applied including the twelfth check digit.

Does this validate CUSIP or SEDOL fields?

Not directly—those have their own national rules. An ISIN embeds a country-specific NSIN; this page checks the ISO wrapper and checksum only.

Common search terms

Phrases people search for that match this tool. See the full long-tail keyword index.

  • isin validator online iso 6166
  • international securities id check digit
  • validate isin luhn in browser
  • securities identifier checksum no upload

More tools

Related utilities you can open in another tab—mostly client-side.