Routing Number Validator
ValidatorValidate US ABA routing numbers instantly. Verifies the mod 10 check digit and decodes the Federal Reserve district and institution type. Free, runs in your browser.
About this tool
About the Routing Number Validator
This validator checks US ABA routing numbers (also called routing transit numbers or RTNs) using the official mod 10 checksum algorithm banks use to catch typos before a wire or ACH transfer is processed. Enter any 9-digit routing number and the tool instantly verifies the check digit and decodes the Federal Reserve routing symbol.
The first two digits of a routing number identify its category: 00-12 for Federal Reserve check-processing districts, 21-32 for thrift institutions, 61-72 for electronic/ACH-only routing symbols, and 80 for traveler's cheques. This tool decodes that range and, for the twelve numbered Federal Reserve districts, names the district (Boston, New York, and so on). It also breaks the number into its Federal Reserve symbol, institution identifier, and check digit for a full field-by-field view.
Use this validator to catch a mistyped routing number before submitting a wire transfer, ACH payment, or direct deposit form, to sanity-check a routing number pulled from a check image in a KYC or fintech onboarding flow, or to understand what a given routing number's prefix actually means.
All validation runs locally in your browser using pure arithmetic — no routing number is ever sent to a server, logged, or stored. The same mod 10 checksum this tool implements is the one used industry-wide by US banks.
Key Features
- Official ABA mod 10 check digit validation
- Decodes Federal Reserve district, thrift, electronic, and traveler's cheque ranges
- Names all twelve numbered Federal Reserve districts
- Field-by-field breakdown: symbol, institution ID, check digit
- Three real, hand-verified example routing numbers to try
- 100% browser-based, no data sent
FAQ
Routing Number Validator — Frequently Asked Questions
How is the routing number check digit calculated?
Each of the 9 digits is multiplied by a repeating weight of 3, 7, 1, 3, 7, 1, 3, 7, 1 (left to right), and the products are summed. A genuine routing number's weighted sum is always a multiple of 10 — this is the mod 10 check built into every ABA routing number.
What do the first two digits of a routing number mean?
They identify the Federal Reserve routing symbol range: 00-12 is a Federal Reserve check-processing district (01 Boston through 12 San Francisco), 21-32 is the equivalent range for thrift institutions, 61-72 is used for electronic/ACH-only routing symbols, and 80 is reserved for traveler's cheques. Any other prefix does not correspond to an assigned range.
Can this tool tell me which bank owns a routing number?
No. The routing number format only encodes the Federal Reserve district and institution identifier — it does not include a public bank-name lookup table, and no such table is available as open data. This tool validates the math and decodes the district only.
Why does my routing number fail even though it has 9 digits?
A 9-digit number can still fail for two reasons: the mod 10 check digit doesn't match (usually a typo in one digit), or the first two digits don't fall into any assigned range. Both cases mean the number is not a valid, issued ABA routing number.
Tips
- Routing numbers are always exactly 9 digits — no letters, spaces are stripped automatically
- The routing number is usually the first group of numbers on the bottom-left of a US check, before the account number
- Use the Routing Number Generator to create checksum-valid test numbers for QA and development
- A valid check digit does not guarantee the number is assigned to a real bank — only that it's correctly formatted
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