United States Banking Institution Account Number Regular Expression?

Question

I have been tasked to \"verify\" the length of a U.S. Banking Institution ACCOUNT NUMBER for a web app I\'m developing. I cannot find anything through SOF, Google, Fed reser

Answer 1

Very interesting. It seems like all routing/transit numbers are 9 digits.

I just checked American Express's online bill pay, for bank accounts they limit their field to 15 numerics. Chase limits theirs to 17. I would probably continue checking and maybe start to call a few banks to find out what their specifications are. It doesn't seem like there is a standard.

Another potential way to determine the length would be to ask the company that performs the transaction. Where does the account number get used? They should have specifications on what they will accept.

Answer 2

In Addition to the other great answers here, i think its helpful to know that routing numbers in the United States include a checksum digit which can be helpful for quick validation that the user typed it in correctly

http://www.brainjar.com/js/validation/

basically all US routing numbers should pass the following test:

3 * (digits[0] + digits[3] + digits[6]) +
7 * (digits[1] + digits[4] + digits[7]) +
(digits[2] + digits[5] + digits[8]) % 10 === 0