Quick ways to verify an account number before you use it
The fastest way to check if a bank account number is valid is to call the bank directly using the phone number on the back of a card or statement — not a number from an email or text. Give them the account number and ask them to confirm it belongs to the person or business you think it does. Most banks can verify in under a minute.
If you are sending money to someone new, ask them to confirm the account number back to you out loud, or have them send it through a method you trust. Scammers often send account numbers by email or text with small typos built in — a single wrong digit can send your money to the wrong place, and recovering it is slow and uncertain.
If you already have the account number in writing and want to check it yourself before sending money, there are a few methods that catch common mistakes but do not may provide the account exists or belongs to the right person.
Key Takeaways
- Calling the bank directly using a verified phone number is the only way to confirm an account number belongs to a specific person.
- Account numbers have a check digit built in — a math formula that catches typos — but this only tells you the number is formatted correctly, not that it is real.
- The Luhn algorithm is the most common check digit system used by U.S. banks, and you can run it yourself or use an online tool to spot obvious errors.
- If you are sending money to someone you do not know well, verify the account number by phone before transferring anything.
- A valid-looking account number can still be fake, closed, or belong to someone else — verification by the bank is the only real protection.
Understanding check digits and the Luhn algorithm
Most U.S. bank account numbers use a check digit — the last digit in the account number is calculated from all the others using a math formula. If someone types the account number wrong, the check digit usually will not match, and the system catches it as invalid.
The most common formula is the Luhn algorithm, also called the mod-10 algorithm. It works by doubling every second digit from right to left, subtracting 9 from any result over 9, adding all the digits together, and checking whether the total ends in zero. If it does, the number passes the check digit test.
You do not need to do this math by hand. Several free online tools let you paste in an account number and run the Luhn check instantly. Search "Luhn algorithm checker" or "account number validator" to find one. If the number fails the check, it has a typo. If it passes, the number is at least formatted correctly — but that does not mean it is real or belongs to the person you think it does.
What a valid account number does and does not tell you
A bank account number that passes the check digit test is formatted correctly, but formatting is not the same as being real. The account could be closed, belong to someone else entirely, or be a number someone made up that happens to have valid formatting.
Banks also do not all use the same length or the same check digit system. Some use Luhn, others use different formulas, and some do not use a check digit at all. An account number that fails the Luhn check might still be valid if it belongs to a bank that uses a different system. This is why the check digit catches obvious typos but is not a complete verification.
The only way to know an account number is real and belongs to the right person is to have the bank confirm it. That confirmation has to come from the bank itself, not from the person giving you the number.
How to verify an account number by calling the bank
Start by finding the bank's phone number yourself. Look at a recent statement, a debit card, or the bank's official website. Do not use a phone number from an email, text, or search result — scammers sometimes set up fake bank phone lines.
When you call, tell the representative you want to verify an account number. Have the account number ready, and be prepared to answer security questions if you are calling about your own account. If you are verifying someone else's account, the bank may not confirm details without that person's permission, but they can usually tell you whether the account exists and is active.
Ask the representative to read the account number back to you to make sure you both have the same number. If you are about to send money, this is the moment to stop and confirm everything matches before you proceed.
Using online banking tools to check account numbers
Some banks offer account verification through their website or app. If you are sending money to another account at the same bank, you can usually type in the account number and the system will show you the account holder's name. This is a built-in safety feature that catches mistyped numbers before the transfer goes through.
If you are sending money between different banks, the sending bank's system may also show you the receiving account holder's name before you confirm the transfer. This is called name matching or account verification, and it is one of the best protections against sending money to the wrong place.
Not all banks offer this feature yet, and it is not required by law. If the bank's system does not show you a name, call the receiving bank directly to confirm the account before you send anything.
What to do if you suspect an account number is fake
If someone is asking you to send money to an account number you cannot verify, do not send it. This is one of the most common scam tactics — a fake invoice, a job offer, or a request from someone claiming to be a family member in an emergency, all with an account number that looks real but belongs to a scammer.
If you have already sent money to an account you now think is fake or wrong, contact your bank immediately. The sooner you report it, the better the chance the bank can freeze the receiving account and recover the funds. If the money went to another bank, your bank can file a recall request, but recovery is not may provide and can take weeks or months.
If you received a suspicious request with an account number, report it to the Federal Trade Commission at reportfraud.ftc.gov. If it came through email or text, also report it to your email provider or phone carrier.
Account number length and format by bank type
U.S. bank account numbers are usually between 8 and 17 digits long, depending on the bank. Checking accounts, savings accounts, and money market accounts at the same bank often have different account numbers. If someone gives you an account number that is much shorter or much longer than expected, ask them to double-check it.
Credit unions, online banks, and regional banks may use different formats than large national banks. If you are unsure whether an account number looks right for a particular bank, call that bank and ask. They can tell you immediately whether the length and format match their system.
Never assume an account number is wrong just because it looks different from one you have seen before. The only way to know is to ask the bank.
Frequently Asked Questions
Can I verify an account number without calling the bank?
You can run a check digit test to spot typos, but that only tells you the number is formatted correctly. To confirm the account is real and belongs to the right person, you need to call the bank or use their online verification tool. No third-party website can do this for you.
What if the account number passes the check digit test but the transfer fails?
The account number may be formatted correctly but still be closed, belong to someone else, or have restrictions on incoming transfers. Contact your bank to find out why the transfer was rejected. They can tell you whether the receiving account exists and what the problem was.
Is it safe to give someone my account number?
Your account number alone is not enough for someone to steal money from your account — they also need your routing number and usually your name. However, do not give your account number to anyone you do not trust. If someone asks for it unexpectedly, call your bank using a number you know is real and ask whether they need it.
Can a fake account number still work for a transfer?
If the account number is completely made up or belongs to a closed account, the transfer will fail and your money will be returned. If the number is real but belongs to someone else, the transfer will go through and your money will go to the wrong person. This is why verification before sending is critical.
What is the difference between an account number and a routing number?
The routing number identifies the bank or credit union. The account number identifies your specific account at that bank. You need both to send money between banks. A valid account number at the wrong bank is useless, and a valid routing number with a wrong account number sends money to the wrong account.