A bank routing number is the nine-digit code printed along the bottom-left edge of a personal check that identifies which financial institution holds your account. Every bank and credit union in the United States has at least one routing number, and it’s used whenever money needs to move between institutions, whether that’s a direct deposit hitting your account, a bill payment leaving it, or a check being processed.
Where to Find It on a Check
Flip a check over to the front and look at the bottom. You’ll see a line of numbers printed in a special magnetic ink (called MICR, which stands for Magnetic Ink Character Recognition). That line contains three separate numbers, reading left to right:
- First: The routing number (nine digits)
- Second: Your account number
- Third: The check number for that specific check
Some banks flip the order of the second and third numbers, placing the check number before the account number. If you’re unsure which is which, the routing number is always exactly nine digits long. Your account number may be shorter or longer depending on your bank, and the check number will match the number printed in the upper-right corner of the check.
You may also notice a smaller fraction printed in the upper-right area of the check (something like 12-345/6789). This is the fractional routing number, an older format that encodes the same bank-identification information. It’s rarely needed today, but it still appears on most printed checks as a backup identifier.
What the Nine Digits Mean
Each segment of the routing number carries specific information about the bank:
- Digits 1 and 2: Identify the Federal Reserve District where the bank is located. There are 12 districts across the country, so these two digits narrow down the geographic region.
- Digit 3: Indicates which Federal Reserve check-processing center handles the bank’s transactions within that district.
- Digit 4: Represents the state within the district where the bank sits.
- Digits 5 through 8: Uniquely identify the specific bank within the Federal Reserve system. This is the part that distinguishes your bank from every other institution in the same region.
- Digit 9: A “check digit” calculated from the first eight digits using a mathematical formula. It’s a built-in error detector. If someone mistypes a routing number, the check digit won’t match, and the system flags it.
Why You Might Have More Than One
Your checkbook routing number works for paper checks and typically for ACH transactions (electronic transfers like direct deposit and autopay). But your bank may use a different routing number for wire transfers. This catches people off guard. If you’re setting up a domestic wire transfer, don’t assume the number on your check is the right one. Call your bank or check its website to confirm which routing number to use for the specific type of transfer you need.
Large banks that have merged with other institutions over the years sometimes maintain multiple routing numbers based on the state or region where you opened your account. Two customers at the same national bank could have different routing numbers depending on where their accounts originated.
When You’ll Need Your Routing Number
You’ll use your routing number more often than you might expect. Common situations include:
- Direct deposit: Your employer needs both your routing and account numbers to send your paycheck electronically.
- Automatic bill payments: Utilities, loan servicers, and subscription services often ask for these numbers to pull payments from your checking account.
- Tax refunds: The IRS asks for your routing and account numbers if you want your refund deposited directly.
- Transferring money between banks: Linking an external account at another bank requires the routing number from that institution.
If you don’t have a checkbook handy, you can find your routing number through your bank’s online banking portal or mobile app. Most banks display it on the account details page. You can also call your bank directly or search the ABA routing number lookup tool online.
Is It Safe to Share?
A routing number by itself is essentially public information. It identifies the bank, not you personally, and anyone could look it up. Sharing it alone doesn’t put your money at risk.
The danger comes when your routing number is paired with your account number. Together, those two pieces of information can be used to set up fraudulent ACH withdrawals, make online purchases at retailers that accept bank account payments, or create counterfeit checks. Scammers who obtain both numbers could initiate unauthorized transfers out of your account or use your account details to facilitate illegal transactions.
This is why you should treat your full account number with more care than the routing number. Avoid sharing both numbers over email or text. When you write a check, you’re inherently sharing this information with the recipient, which is normal. But be cautious about giving these details to unfamiliar people or businesses. If you suspect someone has gained unauthorized access to your account information, contact your bank immediately to place alerts or change your account number.