What an ABA Number Is and Why Your Bank Uses It

An ABA number is a nine-digit code that identifies which bank holds your account

The ABA number (also called a routing number) tells the banking system which specific bank to send money to when you receive a transfer. Think of it like a postal address for your bank — it routes funds to the right place. Every bank in the United States has its own ABA number, and some large banks have more than one if they operate multiple processing centers.

ABA stands for American Bankers Association, the organization that originally created this numbering system in 1910. The system has been in use ever since, and it remains the standard way banks identify each other for transfers, bill payments, and direct deposits.

You will see your ABA number printed on the bottom left of your checks, or you can find it by logging into your online banking account or calling your bank's customer service line. It is always nine digits long, and it never changes for your bank — though it may be different if you move your account to a different bank or branch.

Key Takeaways

• Your ABA number identifies your specific bank and is required for wire transfers, direct deposits, and automatic bill payments.
• The nine-digit code appears on the bottom left of your checks and in your online banking account.
• Each bank has its own ABA number, and some large banks have multiple numbers for different processing locations.
• You need both your ABA number and your account number to complete most transfers — the ABA number alone is not enough.

Where to find your ABA number

The easiest place to find your ABA number is on a check from your account. Look at the bottom left corner — you will see a series of numbers. The first nine digits are your ABA number. The next set of numbers (usually longer) is your account number.

If you do not have checks or prefer not to look at them, log into your online banking account. Most banks display your routing number (another name for ABA number) on the main account page or in a section labeled "Account Details" or "Transfer Information." Some banks also list it under "Wire Transfer Instructions."

You can also call your bank's customer service number — usually on the back of your debit card — and ask for your routing number. They will give it to you when ready. The Federal Reserve also maintains a public database where you can search for a bank's ABA number if you know the bank's name and state, though this is rarely necessary.

Why banks need your ABA number

When someone sends you money through a wire transfer, automatic deposit, or bill payment, the sending bank needs to know exactly where to send those funds. Your ABA number tells them which bank to contact. Without it, the money could go to the wrong bank or get delayed while the system tries to figure out where it belongs.

Your employer uses your ABA number and account number together to set up direct deposit of your paycheck. Your utility company uses it to withdraw automatic payments from your account. Any time money moves electronically into or out of your account, both numbers work together — the ABA number identifies the bank, and your account number identifies you within that bank.

The ABA number is also used for ACH transfers (Automated Clearing House), which are the most common type of electronic transfer between personal bank accounts. This is how you might send money to a friend or family member through your bank's online system.

The difference between ABA number and account number

These two numbers work together but do different jobs. Your ABA number identifies your bank. Your account number identifies you within that bank. Think of it this way: the ABA number is like the city, and your account number is like your street address.

You need both numbers to complete a transfer. If you give someone only your ABA number, they cannot send you money because they do not know which account at that bank should receive it. If you give only your account number, they cannot send money because they do not know which bank to contact.

Your account number is usually 8 to 12 digits long, though this varies by bank. It appears on your checks to the right of your ABA number. You should keep your account number private, just like you would a password, because someone with both your ABA number and account number can set up transfers from your account. Your ABA number, by contrast, is public information — it is printed on every check you write.

What happens if you use the wrong ABA number

If you provide an incorrect ABA number, the transfer will usually be rejected before it leaves the sending bank, and the money will be returned to the sender. This is because the banking system checks whether the ABA number matches a real bank before processing the transfer.

In rare cases, if the wrong ABA number happens to belong to a real bank, the money might go to that bank instead of yours. This is why it is important to double-check the number before confirming a transfer. If this happens, contact your bank when ready — they can work with the other bank to retrieve the funds, though this process can take several days.

For this reason, when you are setting up a new transfer for the first time — especially a large one — it is worth calling your bank to confirm you have the correct ABA number before you send the money.

ABA numbers for different types of accounts

Your ABA number is the same whether you have a checking account, savings account, or money market account at the same bank. The number identifies the bank, not the type of account you hold there.

However, if you have accounts at two different banks, each bank will have its own ABA number. If you move your account from one bank to another, your new bank will have a different ABA number. This is why you need to update your direct deposit information with your employer if you switch banks — the new bank's ABA number is different.

Some large banks operate multiple processing centers and may have different ABA numbers for different regions or account types. If you are unsure which ABA number to use, your bank's customer service team can tell you which one applies to your specific account.

Frequently Asked Questions

Is my ABA number the same as my routing number?

Yes, ABA number and routing number are the same thing. Banks use both terms interchangeably. You will see "routing number" more often in online banking systems, while "ABA number" is the official name created by the American Bankers Association.

Can someone steal money from my account if they have my ABA number?

Not with just your ABA number alone. They would also need your account number. Your ABA number is public information printed on every check you write, so it is safe to share. Keep your account number private, just as you would a password.

Do I need my ABA number to receive a wire transfer?

Yes. The person sending you a wire transfer needs both your ABA number and your account number. You should provide both pieces of information together so the money reaches the correct account at the correct bank.

What if my bank has multiple ABA numbers?

Large banks sometimes have different ABA numbers for different processing locations or regions. Check your checks or online banking to see which number is listed for your account. If you are unsure, call your bank and ask which ABA number to provide for transfers to your specific account.

Does my ABA number change if I move to a different branch?

Usually not. Most banks use the same ABA number across all their branches. However, some very large banks have different numbers for different regions. If you move your account to a different branch, ask your bank whether your ABA number has changed.