CUSIP Validator
ValidatorValidate CUSIP (Committee on Uniform Securities Identification Procedures) numbers. Checks the 9-character format and recomputes the official check digit. Runs entirely in your browser.
About this tool
About CUSIP Validator
A CUSIP (Committee on Uniform Securities Identification Procedures) number is the 9-character identifier used to uniquely identify most US and Canadian securities — stocks, corporate bonds, and municipal bonds. It's made up of a 6-character issuer number, a 2-character issue number, and a single check digit. This validator confirms the format and recomputes the check digit to verify the code is internally consistent.
The validator strips whitespace, verifies the 9-character format (letters, digits, and the special characters *, @, # are all allowed in the first 8 positions), maps each of the first 8 characters to its numeric value (0-9 as themselves, A=10..Z=35, *=36, @=37, #=38), doubles every second character's value, sums the decimal digits of each result, and compares the computed check digit against the 9th character.
Use this to verify a CUSIP pasted from a brokerage statement, prospectus, or market-data feed before using it in a trade, to debug why a CUSIP is being rejected by a validation layer, or to sanity-check a CUSIP derived from an ISIN's national securities identifying number (NSIN).
Instant, fully client-side validation with no data ever leaving your browser. Note this checks structural validity only — it does not confirm the CUSIP is actually registered to a real security, which requires access to the CUSIP Global Services database.
Key Features
- Full 9-character format validation
- Supports the full CUSIP character set, including *, @, and #
- Recomputes and compares the official check digit
- Clear error messages for each failure mode
- Verified against real published CUSIPs
- 100% browser-based, no data ever transmitted
FAQ
CUSIP Validator — Frequently Asked Questions
What is a CUSIP number?
CUSIP stands for Committee on Uniform Securities Identification Procedures. It's a 9-character alphanumeric code that uniquely identifies a specific security — stock, corporate bond, or municipal bond — registered in the US or Canada. It's assigned by CUSIP Global Services, operated by the American Bankers Association.
How is the CUSIP check digit calculated?
Take the first 8 characters (6-character issuer number + 2-character issue number), map each to a numeric value (digits are themselves, A=10 through Z=35, and the rare special characters * = 36, @ = 37, # = 38), double the value of every even position, sum the decimal digits of each result, and subtract the total from the next multiple of 10.
Why does my CUSIP fail validation?
The most common cause is a single mistyped or transposed character. Also check that the code is exactly 9 characters with no spaces or dashes — some data sources format CUSIPs with separators that need to be removed first.
What's the difference between a CUSIP and an ISIN?
A CUSIP identifies US and Canadian securities specifically, while an ISIN is a global standard. For most US securities, the ISIN is simply 'US' + the 9-character CUSIP + a separate ISIN check digit — the CUSIP is embedded directly inside the ISIN's NSIN field.
Can CUSIPs contain letters or special characters?
Yes. While many CUSIPs are all-digit, letters are common in the issue-number portion (positions 7-8), especially for different share classes or bond series. The characters *, @, and # are also valid but rare, reserved mostly for older or special-purpose issues.
Tips
- Strip spaces and dashes before validating — some data feeds format CUSIPs with separators that aren't part of the official code
- If the check digit fails, try re-copying the CUSIP from its original source — the most common error is a single transposed character
- For US securities, the CUSIP is embedded directly in the ISIN — check the ISIN Validator tool if you have a full 12-character ISIN instead
- This validator never sends your CUSIP anywhere — the check digit is recomputed entirely in your browser
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