The paper checks you write and other transactions you make with a checking account are identified by a routing number and checking account number. These numbers appear on the lower left of a check. Starting from the left, the first nine digits are the routing number, followed by a non-numeric symbol. Next is the checking account number, which is four to 13 digits long and is followed by another non-numeric symbol and a final string of digits. The last set of digits identifies the individual check.
What the Numbers Mean
Routing numbers are assigned to financial institutions by the American Banking Association. To receive a routing number, the institution must be chartered by the federal government or a state government and be eligible to have an account with a Federal Reserve bank. The routing number identifies the bank, credit union or other financial institution responsible for paying a check or other financial instrument. Routing numbers are used to track transactions and ensure they end up at the right financial institution. The checking account number is assigned by the financial institution. It tells the bank which account funds should be added to or withdrawn from to complete transactions.