A bank transit number and a routing number refer to the same thing in the United States: the nine-digit code that identifies your financial institution on checks and electronic payments. “Transit number” is the older label, left over from the days when paper checks physically moved between clearinghouses, and “routing number” is what most banks and forms call it now. If a U.S. form asks for either one, give the same nine digits printed on the bottom-left of your check.
One caveat before you go looking: in Canada, “transit number” means something else entirely. More on that below.
Why the Same Code Has Two Names
The nine-digit code was created by the American Bankers Association in 1910 and adopted by the banking industry in 1911 to standardize check processing.1American Bankers Association. Routing Number Policy and Procedures Because the original job was to move paper checks between banks, the number picked up the name “transit number.” As electronic payments took over, “routing number” became the common term, but the older word stuck around in a few places. You’ll still see it in the phrase “routing transit number” (RTN), and it lives inside the magnetic ink character recognition (MICR) line printed on every check.
Roughly 22,000 active routing numbers are in use across the country, and each one can only be issued to a federal or state chartered financial institution that a Federal Reserve Bank has determined is eligible for a master account.2American Bankers Association. ABA Routing Number The nine digits carry a built-in checksum: multiply them by a repeating pattern of 3, 7, and 1, add the results, and the total has to be divisible by 10. That math catches most typos before a payment leaves your bank.
The Canadian Exception
If the form in front of you is Canadian, “transit number” is not the same as a U.S. routing number. Canadian banks use a five-digit transit number to identify a specific branch, paired with a three-digit institution number that identifies the bank itself.3CIBC. Transit Number, Institution Number and Account Number Those eight digits together do the same job as the American nine-digit routing number, but they’re formatted differently and aren’t interchangeable.
Cross-border transfers need both systems: the U.S. routing number for the American side, and the Canadian transit and institution numbers (often plus a SWIFT code) for the Canadian side. Confirm which country’s system a form is asking for before you fill anything in.
Where to Find Your Routing Number
The quickest place is a paper check. The routing number sits in the bottom-left corner, printed in magnetic ink and framed by two special symbols. The middle group is your account number, and the shortest sequence on the right is the check number.
No checkbook? Log into your bank’s website or mobile app. The number is almost always shown under account details or settings, and many banks also print it on monthly statements. The Federal Reserve maintains a public routing number directory that can be used to verify any number in the system.4Federal Reserve Financial Services. E-Payments Routing Directory
You may also see a small fraction near the top-right of a check. That’s the fractional routing number, an older format that encodes the same bank-identification information. Banks still print it as a legacy backup, but it isn’t what modern systems read.
ACH and Wire Routing Numbers Can Be Different
One thing that trips people up: some banks use one routing number for ACH transactions and a different one for wire transfers. Larger institutions sometimes maintain separate numbers so each transaction type flows through the correct infrastructure. Using the wrong one will delay or reject the payment.
ACH transfers run through the Automated Clearing House network in batches and typically settle in one to two business days. Wire transfers move through the Fedwire Funds Service, are processed individually, and often complete within hours for domestic transactions.5J.P. Morgan Payments Developer Portal. ACH vs. Wire Transfers and When to Use Each Federal Reserve regulations let banks rely on the routing number in a payment order to identify the destination bank, even if other identifying information conflicts.6eCFR. 12 CFR Part 210 Subpart B – Funds Transfers Through the Fedwire Funds Service The number carries that much weight.
Before setting up a wire, call your bank or check its site to confirm whether it uses separate numbers for ACH and wire. It takes a minute and prevents a returned transaction or a failed-transfer fee.
International Transfers Use a Different Code
Your ABA routing number only works for domestic U.S. transactions. International wire transfers rely on SWIFT codes (also called BIC codes), which are alphanumeric identifiers of eight or eleven characters that locate banks globally. Sending money overseas usually means providing your routing number for the U.S. leg and the recipient’s SWIFT code for the international leg. The two aren’t substitutes.
Keeping the Number Safe
A routing number on its own is essentially public. It’s printed on every check you’ve ever written, and anyone can look up a bank’s routing number online. The risk shows up when it’s paired with your account number. Together, those two pieces can be used to set up unauthorized ACH withdrawals, produce counterfeit checks, or make online purchases at retailers that accept bank account payments.
A few habits help. Don’t send your full account number over email or text. When a business asks for your banking details, make sure you initiated the contact and the request is legitimate. Watch your account for unfamiliar activity, including small test debits that fraudsters use to confirm an account is live before attempting a larger pull. If you spot something wrong, contact your bank right away to freeze the account and dispute the charges.