ISIN Checker
Paste an ISIN to check its structure and check digit. A valid ISIN is split into its country prefix, the national code and the check digit; for US and Canadian ISINs the national code is a CUSIP, and for GB ISINs that start with GB00 it is a SEDOL, and both are checked too.
When only the check digit is wrong, the tool tells you which digit the ISIN should have. The check runs in your browser. Nothing you type is uploaded, stored or logged.
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How an ISIN is built
An ISIN (International Securities Identification Number, ISO 6166) has 12 characters and identifies a security, not a listing: the same share has one ISIN wherever it trades. National numbering agencies, members of ANNA, assign ISINs for the securities issued in their country.
| Part | Example (US0378331005) | What it is |
|---|---|---|
| Prefix | US | ISO 3166 code of the country of the issuing numbering agency, or XS for international securities |
| National code (NSIN) | 037833100 | Nine letters or digits; padded with zeros on the left when the national code is shorter |
| Check digit | 5 | One digit that protects the whole ISIN against typing errors |
How the check digit is calculated
- Replace every letter of the first 11 characters by two digits: A = 10, B = 11 and so on up to Z = 35.
US037833100becomes3028037833100. - Starting with the rightmost digit, double every other digit and write the products as single digits (12 becomes 1 and 2).
- Add all the digits. The check digit is the amount needed to reach the next multiple of 10 (the Luhn algorithm).
National codes inside an ISIN
| Prefix | National code | Example |
|---|---|---|
US, CA | The 9-character CUSIP, check digit included | US0378331005 holds CUSIP 037833100 |
GB (GB00...) | The 7-character SEDOL after two zeros | GB0002634946 holds SEDOL 0263494 |
XS | A common code allocated for international securities held in the international central securities depositories | XS2324321285 |
| Other countries | A code set by the numbering agency of that country | AEE000301011 |
Where ISINs appear in messages
In MT securities messages the security is identified in field 35B as the word ISIN, a space and the ISIN, for example :35B:ISIN US0378331005 in an MT540 or an MT535. In ISO 20022 it is FinInstrmId/ISIN, for example in a sese.023. A wrong or unknown ISIN in a settlement instruction is reported in the MT548 with reason DSEC.
Questions
- What does this ISIN checker check?
- That the ISIN has 12 characters, starts with two letters, has letters or digits in the middle and a digit at the end, and that the check digit is right. For US, CA and GB ISINs it also checks the CUSIP or SEDOL inside.
- Does a valid ISIN mean the security exists?
- No. A valid ISIN is well formed. To see which instrument it belongs to, look it up with the security lookup on zagtrader.com, or ask the numbering agency of the country.
- What is the difference between an ISIN and a CUSIP?
- A CUSIP is the 9-character national code for US and Canadian securities. The ISIN of such a security is US or CA, the CUSIP and one more check digit.
- What does an XS ISIN mean?
- XS is used for international securities, mostly Eurobonds, that settle in the international central securities depositories rather than in one national depository.
- Is my ISIN sent to a server?
- No. The check runs in your browser and nothing is uploaded. The optional FIGI lookup is a separate tool and says what it sends.
- How do I calculate an ISIN check digit?
- Turn letters into numbers (A = 10 to Z = 35), double every second digit from the right, add all the digits and take the amount needed to reach the next multiple of 10. The tool does this for you and shows the expected digit.
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Format checks only. A valid result does not confirm that an account, institution or payment exists. Swift is a trademark of S.W.I.F.T. SC; ZagTrader is not affiliated with or endorsed by Swift.