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🏦 ABA Routing Number Checker & Validator
Free ABA routing number checker to validate US bank routing numbers instantly. Confirm 9-digit length, verify the checksum, and catch common errors.
ABA Routing Number Checker
Validate US routing numbers with inline formatting, checksum math transparency, and copyable validation reports.
Digits only: -
Routing number must be exactly 9 digits.
Unavailable until at least 2 digits are entered.
Checksum breakdown
| Pos | Digit | Weight | Product |
|---|---|---|---|
| 1 | - | 3 | - |
| 2 | - | 7 | - |
| 3 | - | 1 | - |
| 4 | - | 3 | - |
| 5 | - | 7 | - |
| 6 | - | 1 | - |
| 7 | - | 3 | - |
| 8 | - | 7 | - |
| 9 | - | 1 | - |
Weighted sum: 0Sum mod 10: 0Rule: valid when 9 digits and mod 10 equals 0
How to use this tool
- Enter or paste a routing number. Non-digits are stripped automatically.
- Review the validity badge and reason text.
- Use the checksum breakdown table to verify math line-by-line.
What this validates
- Digit count (must be exactly 9).
- ABA checksum using 3-7-1 weighting.
- Prefix range context for routing symbol classification.
What this does not validate
- Institution activity status in real-time directories.
- ACH vs wire-specific account setup rules.
- Account-number pairing correctness.
FAQ
- Does a checksum pass guarantee the bank account is usable?
- No. It confirms structural validity only. You still need institution and account verification.
- Why are spaces allowed in input?
- Formatting helpers keep the field readable, but validation uses digits only.
- Can I export results for audit logs?
- Yes. Use copy or download report actions to capture machine-readable output.
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