ABA is the routing number that tells the banking system where to send your money
An ABA number is a nine-digit code that identifies which bank or credit union holds your account. When you send money to someone else's account—whether by wire transfer, ACH payment, or check—the ABA number is how the banking system knows which institution to route that money to. Without it, the payment would have nowhere to go.
The acronym stands for American Bankers Association, the organization that created and maintains the system. Every bank, credit union, and savings institution in the United States has its own ABA number. If you have accounts at two different banks, each one has a different ABA number, even if you're the same person.
You'll also hear ABA numbers called routing numbers or routing transit numbers—these terms mean the same thing. The number appears on the bottom left of your checks, and your bank can tell you the number if you call or log into your online account.
Key Takeaways
- Your ABA number identifies your specific bank or credit union and is required for wire transfers, ACH payments, and direct deposit setup.
- The nine-digit code appears on the bottom left of your checks and is different for each institution, even if you use the same bank in different cities.
- You need both the ABA number and the account number to move money into or out of your account; the ABA alone is not enough.
- The ABA number is public information—sharing it does not put your account at risk the way sharing your full account number would.
Where the ABA number appears and how to find it
If you have checks, the ABA number is printed on the bottom left edge, before your account number. It's always nine digits. You can also find it by logging into your bank's website or mobile app—most institutions display it in the account details section, sometimes labeled as "routing number" or "ABA code."
If you don't have checks or online access, call your bank's customer service line. They can give you the number in under a minute. Some banks also print the ABA number on statements, though not all do.
One important detail: if your bank has multiple branches or locations, they all share the same ABA number. The ABA identifies the bank itself, not the individual branch. So whether you opened your account in New York or California, the routing number stays the same.
Why you need it for different types of payments
When you set up direct deposit for your paycheck, your employer needs your ABA number and account number to route the deposit to the correct bank. Without the ABA, the payroll system wouldn't know which institution to send the money to, and the deposit would fail.
For wire transfers—moving money quickly to another bank—you must provide the ABA number of the receiving bank. The sending bank uses it to connect with the correct receiving institution through the Federal Reserve's wire transfer network. This is why wire transfers are fast: the ABA number gets the money to the right place when ready.
ACH payments (the system behind most bill payments and peer-to-peer transfers) also require the ABA number. When you pay a bill online or send money through an app like Venmo or PayPal, the system uses the ABA to route the payment through the ACH network, which typically takes one to three business days.
Even old-fashioned checks rely on the ABA number. When someone deposits your check, the bank reads the ABA number at the bottom to know where to send the funds for collection.
ABA numbers are public—account numbers are not
Your ABA number is not sensitive information. It's printed on every check you write and is the same for thousands or millions of customers at your bank. Sharing your ABA number alone does not put your account at risk.
Your account number, by contrast, is private. Combined with your ABA number, it identifies your specific account. This is why you should never share your full account number with someone you don't trust, but giving out your ABA number is safe. Many businesses and government agencies publish their ABA numbers publicly so people can send them payments.
If you're worried about fraud, the risk comes from someone having both your ABA number and your account number together—or from having access to your online banking login. The ABA number alone tells someone which bank you use, nothing more.
How the ABA system connects to the broader banking network
The ABA number is part of the infrastructure that connects all U.S. banks and credit unions. When you send money to another account, your bank and the receiving bank use the ABA number to find each other in the Federal Reserve's system and complete the transfer.
The Federal Reserve maintains the master list of all ABA numbers and which institution each one belongs to. Banks query this database every time they process a payment to confirm the receiving bank exists and is still active. If you enter an incorrect ABA number, the receiving bank's system will usually reject it before the money leaves your account.
This system has been in place since 1910 and is one of the reasons the U.S. banking system can move trillions of dollars daily with relatively few errors. The ABA number is a small but essential piece of that machinery.
What happens if you use the wrong ABA number
If you enter an incorrect ABA number when setting up a transfer, one of two things usually happens. Most modern banking systems will reject the transaction before it processes, telling you the routing number is invalid. This is the safer outcome—your money stays in your account.
Occasionally, a transaction will go through to the wrong bank. If this happens, contact your bank when ready. They can attempt to recall the payment, though success depends on whether the receiving bank has already processed it. The longer you wait, the harder it is to recover the money. Wire transfers are harder to reverse than ACH payments, which is why accuracy matters more for wires.
This is why it's worth double-checking the ABA number before you confirm any large transfer. Ask the receiving party to confirm it, or look it up yourself using your bank's routing number search tool.
ABA numbers for different types of institutions
Banks, credit unions, and savings institutions all have ABA numbers. A credit union's ABA number works exactly the same way as a bank's—it identifies the institution in the payment system. If you have an account at a credit union, you'll use its ABA number for direct deposit, wire transfers, and ACH payments just as you would with a bank.
Online banks and fintech companies that hold deposits also have ABA numbers assigned by the Federal Reserve. If your money is held at an online bank, that bank has its own routing number, even though you've never walked into a physical branch.
Some financial services companies (like payment apps or investment firms) don't have their own ABA numbers because they don't hold deposits directly. In those cases, your money is held at a partner bank, and you'd use that partner bank's ABA number for transfers.
Frequently Asked Questions
Can I use the same ABA number for all my accounts at the same bank?
Yes. If you have a checking account and a savings account at the same bank, they share the same ABA number. The ABA identifies the bank, not the individual account. You'll use the same routing number for both accounts, but you'll specify which account by providing the account number.
Is my ABA number the same if I move to a different state?
Yes. The ABA number identifies your bank as an institution, not your location. If you move and keep your account open at the same bank, the routing number doesn't change. If you close your account and open a new one at a different bank, you'll get a new ABA number.
What's the difference between an ABA number and a SWIFT code?
An ABA number routes payments within the U.S. banking system. A SWIFT code is used for international wire transfers and identifies banks globally. If you're sending money to someone outside the U.S., you'll need their bank's SWIFT code, not the ABA number.
Can someone steal money from my account if they have my ABA number?
No. Your ABA number alone doesn't give access to your account. Someone would need both your ABA number and your full account number to attempt an unauthorized transfer, and even then, most banks have fraud detection systems in place. The real risk comes from sharing your account number or your online banking credentials.
Do I need to memorize my ABA number?
No. You can look it up whenever you need it—on your checks, in your online banking portal, or by calling your bank. Most people don't memorize it because they rarely need to type it in manually. Your bank will have it on file for direct deposit and automatic payments.