Account Number

These numbers are the lengthy digits at the bottom of paper checks or on the backs of credit cards.

Author: Elliot Meade
Elliot Meade
Elliot Meade
Private Equity | Investment Banking

Elliot currently works as a Private Equity Associate at Greenridge Investment Partners, a middle market fund based in Austin, TX. He was previously an Analyst in Piper Jaffray's Leveraged Finance group, working across all industry verticals on LBOs, acquisition financings, refinancings, and recapitalizations. Prior to Piper Jaffray, he spent 2 years at Citi in the Leveraged Finance Credit Portfolio group focused on origination and ongoing credit monitoring of outstanding loans and was also a member of the Columbia recruiting committee for the Investment Banking Division for incoming summer and full-time analysts.

Elliot has a Bachelor of Arts in Business Management from Columbia University.

Reviewed By: Austin Anderson
Austin Anderson
Austin Anderson
Consulting | Data Analysis

Austin has been working with Ernst & Young for over four years, starting as a senior consultant before being promoted to a manager. At EY, he focuses on strategy, process and operations improvement, and business transformation consulting services focused on health provider, payer, and public health organizations. Austin specializes in the health industry but supports clients across multiple industries.

Austin has a Bachelor of Science in Engineering and a Masters of Business Administration in Strategy, Management and Organization, both from the University of Michigan.

Last Updated:November 29, 2023

What is an Account Number?

The lengthy digits at the bottom of paper checks or on the backs of credit cards are surely familiar to you. It is obvious that these numbers are used in financial transactions, but what do they mean? What are they made of, and how do they work?

The bank knows where to add or subtract money based on your account number when transactions are posted. Keeping your bank account numbers private is crucial for this reason. If not, someone could be able to access your accounts illegally using your details.

This article will examine the precise origins and significance of these numbers. I will discuss how to locate them and the distinctions among frequently used numbers, including account, routing, and credit-card numbers. 

Ultimately, it will examine how these numbers are gradually being replaced by more advanced security and verification procedures that are less prone to mistakes and fraud.

Key Takeaways

  • You are given a special account number for each new account you establish. The routing number can be the same if your new account is with the same bank.

  • Two-step verification passwords are used by modern technology-oriented businesses to reduce hazards to user accounts.

  • Before giving access, the account number is utilized to send a request for financial authorization to the proper owner, hence enabling various forms of commercial operations.

  • A checking account number is the most frequent sort of account number, as it identifies the owner and enables access, allowing for many types of commercial activities. It is sent to the payment processor to direct transaction authorization requests to the owner.

  • The Social Security Number is a similar identifier to the account number in that its main function is to track the earnings history of U.S. workers to establish their benefit entitlements. Nowadays, checking account number is utilized in financial activities worldwide.

Understanding an Account Number

A specific bank account is identified by a special string of numbers, letters, and other characters called an account number. These are a standard part of almost all financial transactions. Routing and credit card numbers are a few examples.

Although bank accounts have existed since prehistoric Mesopotamia, account numbers are more modern. The concept of financial account numbers as we know them now is said to have emerged with the advent of computers in banking in the late 1960s. 

Account and routing numbers have since been used to identify financial organizations and account individuals securely.

Each bank in the US allocates account numbers based on a unique approach that is kept secret for security reasons. As a result, most bank account numbers are between 8 and 12 digits long, although they can also be between 5 and 17. 

Financial institutions may also utilize two-step verification, multi-factor authentication, and other security procedures to safeguard account numbers against fraud.

Every financial transaction includes at least two account numbers: one that identifies the source of the funds and another that identifies the destination of the funds.

Although it functions as the financial account's fingerprint, it also links to other data. For instance, physical address, contact information (phone and email), account balance, and account age.

An individual may have several accounts, each with a distinct account number. In addition, account numbers could alter if one bank combines with another or buys another bank. Legally, banks are required to inform account holders of any changes to their accounts.

What is A Routing Number

Every financial institution is given a distinct routing number, just like every bank account is given a distinct account number. RTNs (Routing Transit Numbers) or ABA (American Bankers Association) routing numbers are the names given to these financial institutions routing numbers.

A routing number is a nine-digit string of numbers. While bigger international banks may have many routing numbers depending on location, small financial institutions normally have just one. 

Only financial institutions with federal or state charters qualified to keep an account at a Federal Reserve Bank are given routing numbers. 

The relevant routing numbers might alter if two banks merge or if one bank buys another. The Federal Reserve Processing Symbol describes the first four digits of a routing number.

1. The first two digits

Usually, the first two digits are a number between 01 and 12. The Federal Reserve District Office head branch, which the bank is a part of, is indicated by these numerals. 

The Districts, sometimes including neighboring states, run from 01 in Boston to 12 in San Francisco. Non-bank payment processors are given a number between 61 and 72, while travelers' checks are 80.

2. The third digit

The third digit identifies the bank's district-assigned Regional Federal Reserve Processing Center. For instance, "1" would denote the first bank check processing facility.

3. The fourth digit

The fourth digit indicates the bank's location within a Federal Reserve District. A bank with a Federal Reserve District address is given the designation "0." Depending on the Federal Reserve District's state, the numbers 1 through 9 are utilized.

The American Bankers Association awarded the bank a unique identifying code of digits five through eight.

4. The last digit of the routing number is known as a "check digit"

Whereas the other numbers pertain to identifying information about the individual financial institution, the check digit is derived using the other eight digits to confirm the validity and avoid fraud. (Thus, "check" is used in the sense of "verify" rather than "paper check.")

Account Number vs. Routing Number

A routing number and an account number are required for each bank-related financial transaction. The routing number is used to identify the specific bank. The account number (typically 10-12 digits) identifies the client's account.

Routing numbers allow financial organizations to trace where monies come from and where they go. Therefore, financial institutions must have routing numbers to perform direct deposits, check deposits, loan payments, and wire transfers.

Ans are distinctive to a particular bank account. Clients can have several accounts, each with its own account number, although the routing number (the financial institution that maintains the customer's account) stays the same.

The routing number is the nine-digit number found in the bottom left corner of a paper check. A paper check's account number is a 5-17 digits string in the bottom right-hand corner.

The routing number on a check indicates the location of the account. The account number denotes a specific bank account and its account information.

For paper or check transfers, ABA (American Banking Association) routing numbers are used to identify the financial institution. Routing numbers for ACH (Automated Clearing House) transfers indicate the clearinghouse utilized for an ACH transfer.

An ACH transfer is a method of sending or receiving money electronically. The clearinghouse is the designated financial intermediary responsible for validating and finalizing transactions between a buyer and a seller. All routing numbers, including ACH, are included in ABA routing numbers.

What are credit card numbers?

A credit card number is 16-digit on the front or back of a credit card. It contains information on the card issuer and the client's account. The Issuer Identification Number is the first six digits (IIN).

The first digit is the Major Industry Identifier (MII). The MII identifies the card issuer's industry. As an example:

  • Airlines' credit cards have an MII of 1.
  • The MII for the entertainment and travel businesses is 3. (this includes Diners Club and American Express)
  • The MII for Visa cards is 4.
  • MasterCard's MII is 5.
  • The MII of Discover is 6.
  • MIIs 7-9 are designated for the petroleum and healthcare industries and national standards organizations.

The following five digits indicate which bank or network issued the card. The IIN of all cards issued by the same bank and program is the same. As an example:

  • An IIN of 475050 denotes a JPMorgan Chase Visa card (4). (75050)
  • An IIN of 526219 denotes a Citibank MasterCard (5). (26219)
  • If a credit card program is large enough, it may be allocated many IINs. Bank of America Visa cards, for example, have numerous potential IINs.

Digits 7-15 represent a distinct credit card account number. This number is distinct from any bank account numbers held by the cardholder. This is because many consumers have credit cards from financial entities other than banks.

It is simpler to replace a lost or stolen credit card without impacting the cardholder's bank account, and it can also assist in avoiding fraud.

The last digit of a credit card number is the "check digit," which acts similarly to the last digit of a routing number. It is created automatically by applying the Luhn Formula to the credit card's last fifteen digits and may be used to validate the complete credit card number.

How a Bank Account Number Works

In the case of a paper check, the account number is usually found towards the bottom, between the routing number and the check number. From the left, the first set of numbers represents the 9-digit routing number, the middle group represents the account number, and the third group represents the check number.

The arrangement method was created in 1910 to help sort checks before distributing them to the right owners. The account number is utilized to send payments to the appropriate party for the same purpose. However, the check number and account number might occasionally be mixed up.

The paper checks bottom has the number of the checking account. The bottom of the check has three sets of numbers in a computer-readable font:

  • The nine-digit bank routing number is the first number on the left.
  • Your account number is the middle digit.
  • The check number appears as the third number.

Bank account number typically range from eight to twelve digits.

Payroll processing companies use checking account information to develop a direct employee payment system.

The bulk of financial transactions made by retailers is associated with account numbers. For example, account numbers are assigned credit card accounts, sales receipts, and gym memberships.

Protecting Account Numbers From Fraud

Account numbers, like passwords, are especially vulnerable to fraud and identity theft. It explains why a series of vexing queries hamper the ordinary modification of account numbers.

More changes are now being made to make it even less vulnerable to hackers. Password managers, for example, when paired with a multi-factor authentication system, make it harder to circumvent security measures.

To obtain access to client account numbers and other highly classified and sensitive data, modern techno-savvy organizations typically adopt an unreasonably difficult master password.

Accounts that use multi-factor authentication, which adds a second security layer to safeguard an account, are becoming more common. 

Customers, for example, must enter biometric data, voice activation, or a time-sensitive code received to their email or mobile phone to access their accounts.

Regardless, the security-enhancing measures are not completely impenetrable. For example, hackers can still gain unauthorized access to accounts when they get authentication elements.

Malware, an account recovery procedure, or phishing are some means for intercepting such data. As a result, modern firms strive to protect consumers' account details in an increasingly dangerous internet world.

Hackers and fraudsters employ various strategies and tactics to steal your personal information and, eventually, your money. Here are some examples of frequent sorts of scams to avoid:

  • Phishing scams: these scams include criminals gaining access to personal information via bogus emails, websites, and text messages that look to be from respectable organizations.
  • Scams involving bank account deposits: email scams that ask you to utilize your bank account to transfer a significant sum of money in exchange for a charge.
  • Scams using cold calling: the fraudster will call you and pretend to be from your bank. The caller will pretend that your account has been compromised and ask for your information, saying they will move your funds to a new, secure bank account.

If you are wondering how to secure your bank account against fraud, here are six efficient methods for safeguarding your personal information and money online:

  1. Update your software and apps regularly.
  2. Make use of two-factor authentication.
  3. Use social media with caution.
  4. Make use of a password manager.
  5. Check your credit report regularly.
  6. Be wary of any email you receive.


Identifying a client during a bank-related financial transaction necessitates using two pertinent pieces of information: the account number and the routing number. A unique set of information is assigned when creating an account with a financial institution.

An account number is unique to the account holder and functions similarly to a customer's fingerprint or ID. Similarly, the routing number contains unique numerical codes that may be used to identify each banking institution, which is made possible by the International Bank account number (IBAN).

In the United States, the routing number is nine digits long, proving that the designated financial institution has an account with the Federal Reserve and is state or federally chartered. It is most commonly used when paying taxes or rearranging checks.

In contrast, account number is used with the routing number to identify a customer's digital account. In addition, it has between eight and twelve digits. Therefore, if a person has twin accounts at the same bank, the bank AN will be different, but the routing number will be the same.

Researched and authored by Oday Najad LinkedIn

Reviewed & Edited by Ankit Sinha LinkedIn

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