Support Guide
The most frequent mistakes people make with ABA routing numbers — wrong length, transposed digits, wrong routing number type, and how each error affects your transfer.
You do not need to leave this guide to run a structural check. Use the same validator here, then continue reading if you need more context.
Bank Details
Paste full bank details — routing number (ABA) and account will be detected automatically.
This tool validates format only. It does not verify whether the bank account exists or can receive payments.
The routing number must be exactly 9 digits. The most frequent cause of length errors is copying only part of the MICR line from a check — accidentally including a boundary symbol as a digit, or misreading the boundary between the routing number and account number.
An 8-digit input almost always means the leading zero was dropped. Some routing numbers begin with 0 — for example, 071000013 for US Bank. If you are copy-pasting from a source that stripped leading zeros, add the leading zero back.
A 10-digit input usually means one digit from the account number was included. On the MICR line, routing and account numbers are adjacent — without the boundary symbols it is easy to grab one extra digit.
The ABA 3-7-1 checksum catches most single-digit transcription errors. If you enter a routing number with the correct 9-digit length but the checksum fails, one digit is almost certainly wrong. Common patterns include transposing two adjacent digits (e.g., 123 → 132), misreading a 6 as an 8, or duplicating a neighboring digit.
If the checksum fails, do not guess or try variations. Obtain the correct routing number directly from the bank — either from their website, from a check, or by calling customer service.
Note that passing the checksum does not confirm the routing number routes to the correct bank — it only confirms the number is structurally valid. A routing number from a bank that has since been acquired or closed may still pass the checksum but route incorrectly.
Large US banks maintain separate routing numbers for checks, ACH transactions, and wire transfers. Using the check routing number for an ACH direct deposit will often work, but using it for a wire transfer may fail. Many banks have specific wire routing numbers that differ from their ACH numbers.
International wire transfers additionally require SWIFT BIC codes. If you are wiring funds internationally, confirm with your bank whether a routing number or SWIFT BIC is required — and get both if possible.
When in doubt, call your bank and ask specifically: 'What is the routing number for incoming ACH / domestic wire / international wire payments?' This 30-second call prevents the most common cause of misdirected transfers.
The most common reason is using the wrong routing number for the transaction type. Confirm with your bank that the routing number is correct for the specific payment method (ACH vs domestic wire vs international wire).
It means one or more digits do not satisfy the ABA weighted checksum formula. This is almost always caused by a transcription error — a wrong, missing, or transposed digit. Get the routing number from an authoritative source.
Routing numbers do not technically expire, but they can become inactive after bank mergers or closures. A retired routing number may still pass the checksum but will not route payments correctly.
This tool checks format only. It validates routing number structure and ABA checksum, but does not confirm that a bank account exists, is active, belongs to a person, or can receive payments. It does not perform financial, identity, or bank verification.
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Use the main validator when you need a fast structural check. Use support guides when you need deeper context, implementation detail, or troubleshooting help.
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