Bank account numbers in the United States contain only digits, never letters

Your U.S. bank account number is made up entirely of numbers — typically between 8 and 12 digits, depending on your bank. You will never see letters mixed in. If someone tells you to use letters in your account number, or if you see letters where the account number should be, something is wrong with that instruction or document.

This matters because account numbers are how your bank's computer system finds your specific account among millions of others. The system reads numbers, not letters. Using letters would confuse the routing process and could send money to the wrong place or cause a transaction to fail.

Key Takeaways

  • U.S. bank account numbers contain only digits (0–9), never letters or special characters.
  • Your routing number is also digits-only, though some international transfers may involve letter codes for the bank itself.
  • If a form or instruction asks you to enter letters in your account number field, double-check the source — it may be a mistake or a scam.
  • Account numbers vary in length by bank, but length does not affect whether they contain letters.

Why banks use numbers only for account identification

Banks built their systems around numbers because they are faster and more reliable for computers to process. A number has one meaning; a letter can be misread or typed wrong more easily. When you write down "1" versus "I" or "0" versus "O" by hand, they look similar. Computers reading only numbers avoid this confusion entirely.

Your account number is an identifier, like a Social Security number or a driver's license number. Just as those are digits-only, so is your account number. This standardization makes it possible for banks to move money between institutions without errors.

What those letters might be on your bank documents

You may see letters on your bank statement or check, but they are not part of your account number itself. For example, your statement might show a code like "CHK" (for checking account) or "SAV" (for savings account) next to your account number. These letters describe the type of account, not the account number.

On a check, you will see your routing number and account number printed at the bottom in magnetic ink. Both are numbers only. Above or beside them, your bank may print letters indicating the account type or branch code, but those are separate from the account number itself.

International transfers and SWIFT codes

If you are receiving money from outside the United States, you might hear about a SWIFT code or BIC code. These do contain letters — they identify the bank itself, not your account. A SWIFT code looks like "CHASUS33" and tells the sending bank which U.S. bank to route the money to. Your account number itself is still numbers only.

Some countries use account numbers with letters, but U.S. banks do not. If you are sending money to another country or receiving it from one, the other bank's account number may have letters, but yours will not.

What to do if you see letters in an account number field

If a form, email, or website is asking you to enter letters as part of your account number, stop and verify the source. Legitimate bank forms will never ask for letters in the account number field. This is a common sign of a phishing scam or a fraudulent website pretending to be your bank.

Contact your bank directly using the phone number on your statement or card — not a number from an email or text — and ask whether the form or request is real. Your bank's customer service team can tell you when ready whether they sent it.

How account numbers are structured

Most U.S. banks assign account numbers that are 8 to 12 digits long. Some banks use shorter numbers; others use longer ones. The length varies, but the content does not — it is always digits. The first few digits may identify your branch or account type within the bank's system, but you do not need to decode this yourself. You only need to know your full account number and your routing number to receive or send money.

When you open a new account, your bank will give you your account number in writing or show it to you online. Write it down or save it somewhere safe. You will use it for direct deposits, bill payments, and wire transfers.

Frequently Asked Questions

Can I use letters if my bank's website lets me type them?

No. If a website accepts letters in the account number field, it is either not a real bank website or there is a technical error. Legitimate banking websites will only accept numbers in the account number field. If you are unsure, call your bank directly before proceeding.

What if my account number looks different on different documents?

Your account number should be the same everywhere — on your statement, checks, and online banking. If it looks different, you may be looking at different parts of the number or a different account. Check your most recent statement to confirm your correct account number.

Do I need to memorize my account number?

No, but it is helpful to write it down and keep it in a safe place. You will need it for direct deposits, setting up bill payments, and wire transfers. Your bank statement always shows it if you need to look it up.

Is my routing number also numbers only?

Yes. Your routing number is a nine-digit code that identifies your specific bank branch. Like your account number, it contains only digits. Together, your routing number and account number tell the banking system exactly where to send or receive money.