ABA Number: What It Is and Where to Find It
Last updated 06/11/2026 by
Ante Mazalin
Edited by
Andrew Latham
Summary:
An ABA number is a nine-digit code that identifies a specific U.S. bank or credit union in electronic and paper transactions.
Also called a routing number, it tells the financial system where to send and pull money.
- Nine digits: A fixed-length code unique to each financial institution.
- Created in 1910: Developed by the American Bankers Association to route paper checks.
- Where to find it: The first set of numbers on the bottom left of a check.
- Different uses: Some banks use separate routing numbers for ACH and wire transfers.
Every time a paycheck lands in your account or a bill is pulled from it, an ABA number quietly directs the money to the right bank. It is one of the oldest pieces of plumbing in modern finance, and still essential today.
What an ABA number is
An ABA number is a nine-digit code that identifies the financial institution holding an account. The American Bankers Association created the system in 1910 to make check processing faster and more accurate.
The number works as a bank’s address within the payment system. When money moves, the ABA number tells the network which institution to credit or debit.
It is used alongside your account number, which identifies you specifically, much like a routing number paired with an individual ledger.
Where to find your ABA number
Your ABA number appears in several places, and the easiest is the bottom of a paper check. It is the first nine-digit group printed there.
- On a check: The first set of numbers in the bottom-left corner.
- In online banking: Listed under account details or account information.
- On the bank’s website: Often published on a help or routing-number page.
- By calling the bank: Customer service can confirm the correct number for your transaction.
According to the Consumer Financial Protection Bureau, the routing number identifies your bank and is needed to set up direct deposits and electronic payments.
ABA number vs. account number
People often confuse the ABA number with their account number, but they identify different things. One points to the bank; the other points to you.
| Detail | ABA / routing number | Account number |
|---|---|---|
| What it identifies | The financial institution | Your individual account |
| Length | Always nine digits | Varies by bank |
| Shared by others | Yes, by all customers of the bank | No, unique to you |
You need both numbers together to complete most transfers, since one routes the money to the bank and the other to your specific account.
Good to know: Many banks use one routing number for ACH transfers like direct deposit and a different one for wire transfers. Using the wrong one can delay or reject your transfer.
How ABA numbers are used
ABA numbers route nearly every kind of bank-to-bank movement of money, from automatic bill pay to wire transfers. The transaction type determines which number you need.
How to use your ABA number correctly
- Identify the transaction: Determine whether you are setting up an ACH payment or a wire transfer.
- Get the matching number: Confirm whether your bank uses separate routing numbers for each type.
- Pair it with your account number: Provide both numbers so the money reaches your account.
- Double-check the digits: Verify all nine digits, since one error can misroute funds.
- Confirm with your bank: When unsure, ask your bank for the correct routing number.
Getting the right ABA number matters most for time-sensitive transfers, where a mismatch can bounce the payment back days later.
Related reading on bank transfers
- Routing number is the broader term for the code that identifies your bank.
- Wire transfer explains the fast, direct transfers that often use a separate routing number.
- SWIFT code covers the international equivalent used for cross-border payments.
- Checking account is the account type your ABA number most often points to.
Frequently asked questions
Is an ABA number the same as a routing number?
Yes. ABA number and routing number refer to the same nine-digit code that identifies a U.S. financial institution. The name comes from the American Bankers Association, which created the system.
Where do I find my ABA number on a check?
It is the first set of nine digits printed in the bottom-left corner of the check. Your account number follows it, and the check number comes last.
Why does my bank have two routing numbers?
Many banks use one routing number for ACH transactions like direct deposit and another for wire transfers. Always confirm which number applies to your specific transaction.
Is it safe to share my ABA number?
An ABA number alone is public information and shared by all of a bank’s customers. Risk arises only when it is combined with your account number, so protect that pairing.
Key takeaways
- An ABA number is a nine-digit code identifying a U.S. bank or credit union.
- It is the same thing as a routing number, created by the American Bankers Association in 1910.
- Find it on the bottom-left of a check, in online banking, or on your bank’s website.
- It identifies the bank, while your account number identifies you.
- Some banks use different routing numbers for ACH and wire transfers.
Knowing your ABA number is the first step to setting up direct deposit and electronic payments on a new account. You can compare checking accounts to find one with the transfer features and low fees you want.
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