How to Determine Fractional Routing Numbers

A routing number is a nine-digit bank code used to identify a bank and assist with the transfer of funds between banks. This routing number is sometimes displayed as a fractional routing number in the format ab-cd-e / ffff where "ab" represents the prefix city where the bank is located; "cd" represents the institution id; "e" represents the issuing bank branch number and "ffff" represents the Federal Bank ID number. If you know the traditional routing number of the bank, you can convert the routing number into a fractional routing number.

Step 1

Take the first two digits of the nine-digit routing number, this is the prefix city or region where the bank is located.

Step 2

Take the third and fourth digits of the nine-digit routing number, this is the institution ID for the bank.

Step 3

Take the fifth digit of the nine-digit routing number, this is the issuing bank's branch number.

Step 4

Take the last four digits of the nine-digit routing number, this is the Fed Bank ID number for the issuing bank.

Step 5

Rewrite the routing number in the following format: prefix city - institution ID - issuing branch number / Fed bank number.

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