US Routing Number Validator
Check a US routing number with its check digit.
Runs in your browser. Nothing is uploaded — your input is processed on this device and discarded when you close the tab.
US Routing Number Validator
How to use this tool
- Enter the values in the fields above.
- Press Generate to see the result.
- Use Load sample to try the worked example, Copy result to copy it, or Clear to start again.
Worked example
For 021000021, the check sum is 3 × (0 + 0 + 0) + 7 × (2 + 0 + 2) + (1 + 0 + 1) = 30, and 30 is divisible by 10, so the check digit is valid.
What this tool does not do / Limits
This runs the ABA check digit formula only. It has no live bank database, so it does not confirm that a bank, branch, or account exists, and it must never be used to verify a payee.
Frequently asked questions
Does a valid check digit mean the routing number is real?
No. It only means the digits are self-consistent; a made-up number can still pass.
What does the formula catch?
Single mistyped digits and many transposed digits, which are the most common copying errors.
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