Your account number is the second set of digits printed on the bottom left of a check, and it identifies which specific account at your bank the check draws from.
When you write a check, three pieces of information tell the banking system where the money comes from: your bank's routing number, your account number, and the check number itself. The account number is printed in the MICR line — that row of strange-looking digits at the bottom of the check — right after the routing number. It typically runs 8 to 12 digits long, though the exact length depends on your bank.
The account number stays the same for every check you write from that account. If you have multiple checking accounts at the same bank, each one has its own account number, and each one's checks will show a different number in that position. This is how the bank knows which account to pull money from when someone deposits or cashes your check.
Key Takeaways
- Your account number appears as the second group of digits in the MICR line at the bottom of your check, right after your bank's routing number.
- The account number is unique to that specific checking account and tells the banking system which account to debit when the check clears.
- Account numbers are typically 8 to 12 digits long, but the exact length varies by bank.
- You can find your account number on your checks, your bank statement, or by logging into your online banking portal.
How the MICR line encodes your account information
The MICR line uses a special machine-readable font so that check-processing equipment can read the numbers automatically, without human intervention. The format is always the same: routing number, then account number, then check number. When a check passes through a bank's processing center, a scanner reads these digits and routes the payment to the correct account.
Because the MICR line is standardized across all U.S. banks, any bank can read any other bank's checks. This is why you can deposit a check from someone at a different bank into your account — the routing number tells your bank where to send the money, and the account number tells that other bank which account to pull it from. The check number is there so the issuing bank can track which check was presented and when.
Where else to find your account number
You do not have to look at a check to find your account number. Your bank statement — whether you receive it by mail or view it online — displays your account number at the top or in a summary section. If you use online banking, you can log in and find the account number in your account settings or account details page. Many banks also print it on your debit card or in the welcome materials they send when you open the account.
If you have lost your checks or do not have a statement handy, calling your bank's customer service line is the fastest way to confirm your account number. You will need to verify your identity, but the bank can tell you the number in seconds. Some banks also allow you to view it through their mobile app.
Why your account number matters when writing checks
The account number is what prevents your check from being deposited into the wrong account. If you write a check and someone alters the account number, the money will go to a different account than you intended — which is why check fraud sometimes involves changing the account number rather than the payee name. Banks do verify that the account number on a check matches the routing number (they should belong to the same bank), but they rely on the routing and account numbers being correct as written.
This is also why you should never give out your account number to someone you do not trust. While a routing number is public information — it is printed on every check — your account number is specific to you and should be treated like sensitive financial information. If someone has both your routing number and account number, they can attempt to withdraw money from your account through ACH transfers or other electronic means.
The difference between account number and check number
The check number and the account number are two different things, and it is straightforward to confuse them because they both appear on the bottom of your check. The check number is the third set of digits in the MICR line, and it is also printed in the top right corner of the check in larger type. The check number is unique to that individual check — the next check you write will have a different check number.
The account number, by contrast, is the same on every check you write from that account. The check number is mainly for your own record-keeping; it helps you track which check you wrote to whom and when. The account number is for the banking system to route the payment correctly. When you reconcile your bank statement, you use the check number to match the checks you wrote against the ones that have cleared.
What happens if your account number is printed wrong on a check
If a check has an incorrect account number, the check will either bounce or be deposited into the wrong account, depending on whether the account number matches an actual account at that bank. If the number does not correspond to any real account, the check will be rejected and returned to the person who tried to deposit it. If the number happens to match a different real account, the money will go to that account instead of yours — a serious problem if you are the one who wrote the check.
This is why banks print the account number on your checks in the first place: to reduce the chance of human error. When you order new checks, the bank automatically includes your correct account number in the MICR line. You should never manually write or alter the account number on a check. If you notice that your checks have been printed with the wrong account number, contact your bank when ready and order a new set.
Frequently Asked Questions
Is my account number the same as my routing number?
No. Your routing number identifies your bank; your account number identifies your specific account at that bank. Both appear on your checks, but in different positions in the MICR line. You need both pieces of information for electronic transfers or direct deposits to work correctly.
Can someone steal money from my account if they have my account number?
They would need both your account number and your routing number, plus knowledge of your bank. With that information, someone could attempt an ACH withdrawal or other electronic transfer. This is why you should treat your account number as sensitive information and not share it with people you do not trust, even though the routing number is public.
What if I write a check and realize I used the wrong account number?
Stop payment on that check when ready by calling your bank. You will likely pay a stop-payment fee (typically $25 to $35), but it prevents the check from clearing against the wrong account. Then write a new check with the correct account number. Do this as soon as possible, because stop payments are only effective if the check has not already been processed.
Do I need to memorize my account number?
No. Your account number is printed on your checks and statements, and you can look it up anytime through your bank's website or by calling customer service. You only need to know it when setting up direct deposits, ACH transfers, or wire transfers — and in those cases, you can copy it from a statement or your online banking portal.