How do I validate an ISIN number?

Check that it's exactly 12 characters, starts with a 2-letter country code, has 9 alphanumeric characters in the middle, and the last digit is a valid Luhn check digit. Our free validator tool does all of this automatically.

How do I validate a CUSIP?

A valid CUSIP has exactly 9 alphanumeric characters. The 9th character is a check digit calculated using the modified Luhn algorithm. Enter your CUSIP in our validator for instant verification.

How do I validate a SEDOL?

A valid SEDOL has exactly 7 characters, contains no vowels (A,E,I,O,U), and the 7th character is a check digit calculated using weighted sum with weights 1,3,1,7,3,9 modulo 10.

Financial Identifier Validator

Validate the format and check digit of ISIN, CUSIP, and SEDOL codes instantly. Paste one or more identifiers below.

🔍 Validate an Identifier

📋 Bulk Validation

Paste multiple identifiers (one per line, max 100). Automatically detects type.

Input	Type	Status	Details

How Validation Works

ISIN Validation

✅ Exactly 12 characters
✅ Starts with 2-letter country code
✅ 9 alphanumeric middle chars
✅ Last digit = Luhn check digit
✅ Valid ISO 3166 country code

CUSIP Validation

✅ Exactly 9 characters
✅ 6-char issuer + 2-char issue
✅ Last digit = modified Luhn
✅ Alphanumeric characters only

SEDOL Validation

✅ Exactly 7 characters
✅ No vowels (A,E,I,O,U)
✅ Weighted sum check digit
✅ Weights: 1,3,1,7,3,9

Common Validation Errors

❌

Wrong check digit — most common error. Usually caused by a typo in one of the characters. Try our converter tool to look up the correct identifier.

❌

Wrong length — ISIN must be exactly 12 chars, CUSIP 9, SEDOL 7. Extra spaces or missing characters are the usual culprit.

❌

Invalid characters — SEDOL cannot contain vowels. ISIN must start with letters. CUSIPs are alphanumeric only.

❌

Mixed up identifiers — entering a WKN (6 chars) where a CUSIP (9 chars) is expected. Use our auto-detection to identify the type.