A routing number is the nine digit code that identifies a specific US bank or credit union so checks, ACH transfers and wires reach the right institution. The American Bankers Association created the ABA Routing Number, and it is printed as the left most number at the bottom of every personal check.
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Your routing number says which bank holds the account. Your account number says which account at that bank. Payroll, bill pay, tax refunds and person to person transfers all need both. The ABA routing number policy traces the system back to 1910, when the association devised it, and notes the industry adopted it in 1911.
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A routing number tells the payment system which financial institution should receive or pay a transaction. Banks use it to clear paper checks, to deliver ACH payments such as direct deposit and bill pay, and to send domestic wire transfers. It identifies the institution only, never the individual customer or account.
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Each payment rail reads the routing number a little differently. Checks carry it in magnetic ink so sorting machines can read it. ACH files list it as the receiving institution. Wires sent over Fedwire use it to pick the receiving bank. Wells Fargo describes the routing number and account number together as the pair that completes an electronic transaction over the Automated Clearing House network.
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The ABA says routing data is used to process checks and return items, initiate wire transfers, pre-authorize drafts and handle collections, and the same page puts the count of active nine digit routing numbers at roughly 22,000. That is why a single wrong digit can send a payment back, or to the wrong bank entirely.
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A routing number has three parts. The first four digits are the Federal Reserve routing symbol, the next four identify the institution, and the last digit is a check digit. The check digit lets processing systems catch typos before a payment moves, so a mistyped number is often rejected rather than misrouted.
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The layout below follows the component table in the ABA Routing Number Policy and Procedures:
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The same ABA policy allocates the first two digits by series: 01 through 12 cover checks and electronic transactions of banks and other listed institutions, 61 through 72 are electronic transaction identifiers, and 80 is for travelers checks. Wells Fargo adds that the first two digits identify the Federal Reserve district where the bank is located.
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The ABA policy names the ninth digit as a check digit but does not publish the arithmetic in the section reviewed for this article, so this page does not reproduce a formula. If you need to validate a number, the ABA online lookup is the authoritative check.
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The fastest places are the bottom left of a personal check, your bank's online banking site or mobile app, and your account statement. On a check, the routing number is the first group of digits, followed by your account number and then the check number. Customer service can also confirm it.
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The ABA describes the routing number as the left most number on a check, followed by the account number and then the check number. Huntington lists four places to look: the bottom left corner of a check, Online Banking, the Huntington Mobile app, or a bank statement. Wells Fargo points to account statements and customer service as other options.
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If you do not have checks, sign in to online banking and look under account details or account management. Many banks show a "routing and account number" link right on the account summary. Avoid copying a routing number from a random lookup site when a bank or the ABA source is available.
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Many banks use several routing numbers. Reasons include operating across Federal Reserve districts, mergers that kept older numbers in use, and separate numbers for wires versus checks and ACH. The right number depends on the state where you opened the account and the type of payment you are making.
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Wells Fargo lists three factors behind multiple routing numbers: Federal Reserve processing regions, mergers and acquisitions, and separate numbers for wires, checks and ACH. Huntington publishes a dedicated incoming domestic wire routing number, 044000024, and notes it may differ from the number on your checks because wires run through Fedwire.
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The practical rule: when someone asks for your routing number, ask which payment type it is for. Direct deposit and bill pay use the ACH number. An incoming wire needs the wire number your bank publishes for wires.
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A routing number identifies the bank and is shared by many customers. An account number identifies your individual account and is unique to you. Payments need both: the routing number gets money to the right institution, and the account number gets it into the right account inside that institution.
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Because a routing number is public and shared, it is printed on every check the bank issues and posted on bank websites. Your account number is private. Wells Fargo shows the account number sitting just to the right of the routing number on a personal check. Treat the account number like any other sensitive identifier and share it only with payers you know.
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The American Bankers Association owns the routing number system, and a registrar it designated assigns new numbers. Only federally or state chartered institutions eligible for a Federal Reserve master account can receive one. The Federal Reserve then publishes directories showing which numbers can receive ACH and wire payments.
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The ABA names LexisNexis Risk Solutions as the official registrar, a role the ABA says Bankers Almanac has held for more than one hundred years. Per the same ABA page, a routing number can be issued only to an institution determined eligible for a master account by a Federal Reserve Bank, and the institution must actually be granted that master account at one of the twelve Reserve Banks to access Fed payment systems directly.
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The Federal Reserve Banks publish the E-Payments Routing Directory, which lists FedACH participants and Fedwire participants by routing number. Access requires accepting the Reserve Banks' terms of use, which restrict commercial reuse of the data.
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Routing numbers only work inside the US payment system. They do not identify a bank for most international transfers, they cannot confirm that an account is open, and a correct routing number paired with a wrong account number can still fail or post to the wrong place. Errors are often slow to unwind.
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Three limits are worth knowing. First, a routing number does not prove ownership: anyone can see it on a check, so it is not a security credential. Second, banks with several numbers make it easy to use the wrong one, especially for wires. Third, cross-border payments rely on other identifiers, covered in the SWIFT code guide. For how ACH and wires differ, see ACH vs wire transfer.
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Yes. ABA number, ABA routing number and routing transit number (RTN) all refer to the same nine digit code. The ABA calls it the ABA Routing Number.
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The routing number identifies your bank, not you, and it is printed on every check. The account number is the sensitive part. Share both only with payers you know, such as an employer or the IRS.
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Each routing number is assigned to one institution by the ABA registrar. Different banks have different numbers, though one bank may hold several.
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Yes. Employers need your routing number and account number to set up payroll deposits. See what is direct deposit for the setup steps.
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Use the ABA routing number lookup or confirm with your bank through its website, app or customer service.
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Facts in this article come from pages fetched on October 5, 2026: the ABA Routing Number page, the ABA Routing Number Policy and Procedures, the Federal Reserve Banks' E-Payments Routing Directory, Huntington's routing number help page, and Wells Fargo's routing and account numbers explainer. Bank specific numbers can change; confirm with your bank before sending a payment.
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