ABA Routing Number Validator
Verify US ABA Routing Numbers with the official checksum.
Enter a 9-digit ABA routing transit number to mathematically validate districts and checksums.
What is an ABA Routing Number?
An ABA Routing Transit Number (RTN) is a nine-digit code printed on the bottom of checks in the United States that identifies the financial institution on which it was drawn. It is required for Fedwire transfers and ACH (Automated Clearing House) direct deposits.
Frequently Asked Questions
- How is the checksum calculated?
- The 9th digit is a check digit calculated using a modulo 10 algorithm with weights 3, 7, and 1 applied to the first 8 digits.
- What do the first two digits mean?
- They represent the Federal Reserve routing symbol, indicating which of the 12 Federal Reserve Districts processes the institution's items.
- Are routing numbers used internationally?
- No. ABA routing numbers are strictly for domestic US transfers. International transfers require a SWIFT/BIC code.