Support Guide
A clear explanation of what routing numbers and account numbers do, how they work together, and how to keep your account number secure.
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 9-digit ABA routing number is the bank's address in the US payment system. It tells the ACH network or Fedwire which financial institution should receive the funds. The routing number has nothing to do with the individual account — it only identifies the institution.
Routing numbers are semi-public. All customers of the same bank branch typically share the same routing number (for a given transaction type). Your routing number is printed on your checks, published on your bank's website, and available from customer service. Sharing your routing number alone is low-risk.
However, a routing number by itself is useless for initiating a transfer — it must always be paired with an account number. Think of the routing number as the city and the account number as the street address: you need both to deliver funds.
The account number identifies your specific account at the bank. Together with the routing number, it forms a unique identifier for your bank account in the US payment system. When someone initiates an ACH transfer using your routing number and account number, the funds go directly into (or are pulled from) that specific account.
Account numbers are private. A person who has both your routing number and account number can initiate ACH debit transactions — they can pull money from your account. Only provide both numbers to trusted parties.
Account numbers vary in length by bank — from 4 to 17 digits in the US. There is no universal checksum formula for US account numbers (unlike IBANs in Europe). This is why this validator marks account numbers as 'format plausible' rather than confirmed valid.
Check fraud is the most common misuse of routing and account numbers. If someone obtains a copy of one of your checks — which contains both numbers — they could attempt to create counterfeit checks or initiate unauthorized ACH debits. Never leave blank checks in an unsecured location.
ACH unauthorized transactions are disputable. Unlike card fraud, ACH disputes must typically be reported within 60 days of the statement date. If you notice unauthorized ACH debits, contact your bank immediately.
Entering a wrong account number is a common cause of failed bank transfers. For ACH, most transactions with a wrong account number will return automatically within 1–3 business days. For wire transfers, recovery is harder — always double-check account numbers before wiring.
Yes. Banks can assign you a new account number — usually in response to suspected fraud. When you receive a new account number, you need to update all direct deposit and automatic payment setups.
For ACH, the originating bank will typically receive a return code and the funds are returned within 1–3 business days. For wire transfers, recovery is not guaranteed — always double-check before wiring.
No. The 16-digit number on a debit card is a PAN (Primary Account Number) — a payment card identifier. Your bank account number is separate. They are linked behind the scenes but are different numbers.
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.
What Is an ABA Routing Number?
Everything you need to know about ABA routing transit numbers — their structure, history, how they are assigned, and how they differ from account numbers.
How to Read a US Check — Finding Routing and Account Numbers
A step-by-step guide to the MICR line on the bottom of a US check, including where to find the routing number, account number, and check number.
Common Routing Number Errors and How to Fix Them
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.
Use the main validator when you need a fast structural check. Use support guides when you need deeper context, implementation detail, or troubleshooting help.
Open Routing Number ValidatorACH vs Wire Transfer — What's the Difference?
A practical comparison of ACH and wire transfers — how each works, when to use which, typical costs, settlement times, and routing number requirements.
IBAN vs ABA Routing Number — International vs US Bank Transfers
A complete comparison of IBANs and ABA routing numbers — what each identifies, where each is used, and how to determine which one you need for a payment.