Routing Number Validator
Check a nine-digit US routing number against the ABA mod-10 checksum and the Federal Reserve prefix ranges, before it goes on an ACH form or a wire instruction.
Runs entirely in your browser. Nothing you type is sent to a server.
How the checksum works
The ABA check digit exists to catch the two mistakes people actually make: mistyping a digit, and swapping two adjacent ones. Each position carries a weight of 3, 7 or 1, repeating across all nine digits, and a valid number sums to a multiple of ten.
For 012345672 that is 3(0+3+6) + 7(1+4+7) + 1(2+5+2) = 27 + 84 + 9 = 120, which divides by ten. Change any single digit and the total moves off the multiple, which is why a typo fails immediately. The weights alternate specifically so that transposing two neighbours also breaks it.
What the first two digits mean
A checksum alone is weak protection, because one random nine-digit number in ten passes it. The first two digits narrow it much further: only four ranges are ever issued, and anything outside them is not a routing number at all.
The leading digits also tell you roughly where an account was opened, not where you bank today. 021 is New York, 121 San Francisco, 051 Richmond. A Californian who opened an account while living in New York keeps the New York number.
Wire, ACH and what each costs
A routing number moves money inside the United States. The moment the money leaves the country the cost changes completely, because a bank wire carries an exchange-rate markup of roughly 2-4% that never appears as a fee.
Price a wire before you send with the wire transfer fee calculator, or see what each bank charges in the wire transfer fee guide. Sending abroad from a US account is almost always cheaper through a specialist: compare them here. For an international account number, use the IBAN validator.
Frequently Asked Questions
What is a routing number?
A nine-digit code that identifies the US financial institution holding an account. It was introduced by the American Bankers Association in 1910 to sort paper cheques, and it still routes ACH payments and domestic wires today. It identifies the bank, never the account: you always need an account number alongside it.
Why does my bank have more than one routing number?
Large banks hold separate numbers by state, by product, and often a different one for wires than for ACH. Chase alone has more than twenty. Using the ACH number on a wire is one of the most common reasons a transfer is returned, so take the number from the instructions for the payment type you are actually making.
Does a valid checksum mean the account will receive my money?
No. The checksum only proves the nine digits are internally consistent and the prefix belongs to a real Federal Reserve district. It cannot tell you the bank is still trading, that the number is the right one for a wire rather than ACH, or that the account number you pair it with exists.
Is a routing number the same as a SWIFT code?
No, and confusing them delays money. A routing number is domestic: it moves funds inside the United States. A SWIFT/BIC code identifies a bank internationally. Someone sending you money from abroad usually needs the SWIFT code, and often an intermediary bank as well.
Is it safe to share my routing number?
On its own it is public information, printed on every cheque and listed in the Federal Reserve directory. The risk comes from pairing it with your account number, which together are enough to set up an ACH debit. Share both only with parties you intend to pay you, or to be paid by.
What are the numbers on the bottom of a cheque?
Three groups. The routing number sits on the left between two ⑆ symbols, the account number follows, and the cheque number is last. On some layouts the cheque number comes first. The routing number is always the nine-digit group.
Format and checksum only. This tool does not confirm that a bank is currently accepting payments on the number.