ABA number is also called bank routing number. It is a nine-digit code that is used to identify different banks in the United States of America. It helps other banks in transferring money to and from checking accounts for different types of transaction. These numbers were created by the American Bankers Association in 1910.

How to Find the ABA Numbers?

There are different sources by using which you can get your account’s ABA number. If you have your checkbook then this might be the simplest approach to find this number. The bank routing number lookup is as easy as it may sound.


An ABA routing number is printed on every check. You can find the nine-digit number in the left-hand corner at the bottom of the check. In case of computer generated checks like business checks, it may appear elsewhere. You can even find the ABA routing number on the deposit slips that belong to your bank’s location.


To know the routing number you can even contact your bank. On some bank’s official website this information can be easily retrieved provided you log in to your account. Just search your bank’s site for forms like direct deposit or Automated Clearing House information. You can even check bank routing numbers list online.


Remember, your bank may have multiple ABA numbers so it’s important that you use the one that is associated with your account. It is the same number that is printed on your check. Sometimes due to bank mergers, multiple codes are generated so make sure you use the right one. For confirmation, you can contact the customer service representative. There might be a difference in the number that is used for ordering checks and the one that is used for wire transfers.

How do Banks Obtain Routing Number?

The official ABA Registrar is responsible for assignment of the routing numbers. The company that is responsible for this work is Accuity. Accuity has been serving as the registrar since 1911. These numbers are assigned based on the policy of the Routing Number Administrative Board. Once the institution is organized and is complete it needs to submit an application to Accuity. Another responsibility of Accuity is to publish key to routing numbers. This ABA key to routing numbers is published twice annually so as to keep pace with the changes in the industry.  

How does the ABA routing number work?

Most of the time, you will have to copy the ABA routing number and provide it to whosoever needs it. For providing the same to the employer you need to even give your account number as these details are needed for automatic transfers.

In case of a bank failure, these numbers are regenerated. In such a situation you can contact your bank that whether you can use the old number or not. In most cases, you are allowed to use them until you receive the new checks or apply for the new service.

ABA number acts like an address to your account. That’s why they are even termed as check routing numbers or routing transit numbers. They are printed on the checks using magnetic ink. This ink is machine readable. They are even written in MICR font so that its easy for the systems to recognize the number.

The significance of the digits

  • First 4 digits: These digits were originally assigned by the Federal Reserve Routing System. They represent the bank’s physical location. Due to frequent changes in the bank’s acquisition and mergers, these do not correlate to their geographic location.
  • 5th and 6th digit: It represents the Federal Reserve Bank’s institution that will route the wire and electronic transfers.
  • 7th digit: It designates the Federal Reserve Bank check processing center. This center is assigned to the bank during the initial phase.
  • 8th digit: District of the Federal Reserve Bank.
  • 9th digit: It provides the checksum which is calculated mathematically using the first 8 digits. If the end result and checksum are not equal then the transaction will be flagged and rerouted for manual processing.