Routing Number Validator
Validate a 9-digit ABA bank routing number by its mod-10 weighted checksum, and show whether it is valid, its Federal Reserve district, its check digit, and the full step-by-step checksum calculation. Spaces and dashes are ignored.
Input
Enter a 9-digit ABA routing number. Spaces and dashes are stripped automatically. Validation runs entirely in your browser.
Output
| Property | Value |
|---|---|
| No data yet | |
Guides
Check whether a 9-digit ABA routing number is mathematically valid, in one step. Paste the number and the tool strips any spaces or dashes, confirms it is exactly nine digits, runs the official ABA checksum, and reports the verdict along with the Federal Reserve district, the check digit, and the full weighted-sum calculation.
What is an ABA routing number?
A routing transit number (RTN) is the nine-digit code that identifies a financial institution in the United States. You will find it printed at the bottom-left of a paper check, and it is used to route ACH transfers, wire transfers, and direct deposits to the correct bank. The number is not random: its first two digits encode a Federal Reserve routing symbol, and its last digit is a check digit computed from the other eight so that simple typos can be caught before a payment is sent.
How the checksum works
The American Bankers Association defines a mod-10 weighted checksum. For the nine digits d1 d2 d3 d4 d5 d6 d7 d8 d9, each digit is multiplied by a fixed weight — 3, 7, 1, 3, 7, 1, 3, 7, 1 — and the products are added together:
3·(d1 + d4 + d7) + 7·(d2 + d5 + d8) + 1·(d3 + d6 + d9)
The routing number is valid only when that total is an exact multiple of 10. The ninth digit (d9) is the check digit — it is chosen specifically to make the sum come out even to ten. Because the weights differ, the algorithm catches not just single-digit mistakes but also most cases where two adjacent digits are swapped, which is the most common transcription error.
The tool shows this arithmetic line by line, so you can see exactly which digit contributed what and why a number passes or fails.
How to use it
- Type or paste the routing number into the input field. Spaces and dashes are ignored, so a number copied straight off a check works fine.
- Read the result table: whether the number is valid, which Federal Reserve district its prefix maps to, and its check digit.
- Review the step-by-step checksum breakdown if you want to see the math.
Does a valid checksum mean the account is real?
No. A passing checksum only proves the number is well-formed — that its digits are internally consistent. It does not confirm that the routing number is currently assigned to an active, participating bank, and it says nothing about any account number paired with it. Treat this as a first-line typo check, not proof that money will arrive.
Why is the Federal Reserve district shown?
The first two digits of a routing number are a Federal Reserve routing symbol that indicates which Reserve district originally processed the institution's items. Displaying it gives a quick sanity check that the number's prefix falls in a recognized range.
Is my input sent anywhere?
No. The entire validation runs locally in your browser. Nothing you type is uploaded, logged, or stored.