What Is a Routing Number?

This nine-digit number identifies your bank in a financial transaction. You'll need to know it for tasks like filing taxes or setting up direct deposit.

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You’ve heard of them, you’ve seen them on your bank statement, and many a past employer has requested them. They’re routing numbers: that string of digits lurking in the bottom left corner of your check.

But what are they, anyway?

Routing numbers — nine-digit numbers that identify your bank or credit union in a financial transaction — were adopted by the banking industry in 1910 to make transactions quicker and more efficient. With each bank having one specific number assigned to it, the chances of miscommunication are reduced, for example in the case of two banks with similar names.

When you’ll need your routing number

You’ll need your routing number in a variety of situations, including setting up direct deposit, automatic loan payments or recurring transfers like bill payments.

You’ll also need it when you file taxes to receive your tax refund or debit a tax payment, or when you conduct Automated Clearing House, or ACH, transfers between accounts at different banks.

You will only need your routing number when funds are being directly transferred to or from your bank account — never for debit card or credit card purchases.

How to find your routing number

You can find your routing number at the bottom left corner of your personal checks. It’s the first nine digits of the long line of numbers there. Called the magnetic ink character recognition line, that string of numbers contains your routing number, account number and the check number, listed in that order.

If you don’t have a check handy, you can also find your routing number in the following places:

  • Your bank statement

  • Your bank’s website

  • Through your bank’s phone customer service

  • The American Bankers Association’s routing number lookup

Be aware that routing numbers can change. Financial institutions can close branches, reorganize their operations or change the purpose of a routing number, all of which can affect the number connected to your account, says Jean McCord, senior routing number manager at Accuity, the official ABA registrar for routing numbers. Confirm your routing number with your bank before using it to avoid giving out the wrong number.

Each bank has at least one routing number, although larger banks can have more. At a bank with multiple routing numbers, they can change depending on the location where you opened your account and the type of transaction you’re making.

If you live in Texas, for example, your routing number to set up direct deposit can be different from your friend’s in California, and different from your mom’s when she’s accepting an incoming wire transfer — even if the three of you use the same bank.