To read a check routing number, look at the bottom-left corner of the check: the first group of nine digits, bracketed by two transit symbols that look like a vertical bar with dots on either side (⑆), is the routing number. Those nine digits are not random. They split into three meaningful parts — a four-digit Federal Reserve routing symbol, a four-digit institution identifier, and a single check digit at the end that guards against typos.
Where the Routing Number Sits on the Check
The line of numbers along the bottom edge of a personal check is printed in magnetic ink and is called the MICR line (Magnetic Ink Character Recognition). It always runs in the same left-to-right order: routing number, then account number, then check number.
The routing number is the first block, always nine digits, and it is fenced in by two identical transit symbols. Those symbols belong to a special font called E-13B, which contains only the numerals 0 through 9 and four symbols shaped for high-speed sorting machines to read. The transit symbol marks the start and end of the routing number so scanning equipment can isolate it from the account and check numbers that follow.1eCFR. 12 CFR 229.2 – Definitions
What Each of the Nine Digits Means
Read the nine digits as three groups: positions 1–4, positions 5–8, and position 9.
Digits 1 Through 4: The Federal Reserve Routing Symbol
The first four digits are the Federal Reserve routing symbol. The first two identify which of the twelve Federal Reserve districts the bank belongs to. A routing number that starts with 01 belongs to a bank in the First District (Boston); one that starts with 12 belongs to a bank in the Twelfth District (San Francisco). The third and fourth digits narrow the location further to a specific Federal Reserve Bank branch or processing center inside that district.2eCFR. Appendix A to Part 229 – Routing Number Guide to Next-Day Availability Checks and Local Checks
Thrift institutions — savings banks, savings associations, and credit unions — use a modified prefix. Adding 2 to the first digit signals a thrift. So 21 identifies a thrift in the First District, and 32 identifies one in the Twelfth. A quick way to categorize any routing number: if the first digit is 0 or 1, the bank is a commercial institution; if it is 2 or 3, it is a thrift.2eCFR. Appendix A to Part 229 – Routing Number Guide to Next-Day Availability Checks and Local Checks
Digits 5 Through 8: The Institution Identifier
The next four digits are the ABA institution identifier, assigned uniquely to a specific bank or credit union. Many institutions operate inside each Federal Reserve district, and this four-digit code is what points the payment at the correct one. Together, the first eight digits — routing symbol plus institution identifier — pick out one and only one financial institution in the country.
Digit 9: The Check Digit
The ninth and last digit is a check digit, and it exists purely to catch mistakes. It is calculated from the previous eight using a formula based on modulus 10 arithmetic: each of the first eight digits is multiplied by a fixed weight, those products are summed, and the remainder after dividing by 10 gives the check digit. Mistype any single digit when entering a routing number into a payment form, and the check digit will no longer match what the formula produces. The system rejects the entry before your money moves.
The Fractional Routing Number in the Upper Corner
Many checks also show the routing number in a second, older form near the upper-right corner, written as a fraction. The denominator repeats the same four-digit Federal Reserve routing symbol you see at the start of the MICR line. The numerator adds identifying information such as a city or state code.2eCFR. Appendix A to Part 229 – Routing Number Guide to Next-Day Availability Checks and Local Checks Electronic transactions almost never call for the fractional form, but it is a useful cross-reference if the MICR line is smudged or torn.
Why One Bank Can Have Several Routing Numbers
Reading the number on your check tells you one routing number. Your bank may have more than one, and using the wrong one causes transactions to fail.
ACH, Wire, and Paper Check Numbers Can Differ
Banks often keep separate routing numbers for different transaction types. The number printed on your checks handles paper check clearing. A different number may apply to ACH transactions — direct deposits, automatic bill payments, and person-to-person transfers — and yet another may be required for domestic wire transfers. Confirm which type of transfer you are setting up and use the routing number your bank designates for that purpose. Most banks list all applicable numbers on their website or through customer service.
State-Based Routing Numbers
Large national banks frequently assign routing numbers by the state or region where the account was originally opened, not where the account holder lives today. If you opened your account in one state and later moved, the routing number on your checks may still reflect the original state. Verify the number through your bank’s online portal rather than guessing from your current address.
A Quick Sanity Check Before You Send Money
Once you have read a routing number off a check, a fast visual check can catch obvious problems. Look at the first two digits. Between 01 and 12 means a commercial bank in one of the twelve Federal Reserve districts. A first digit of 2 or 3 means a thrift institution. A routing number starting with a digit higher than 3, outside a few special-purpose codes, warrants extra scrutiny.2eCFR. Appendix A to Part 229 – Routing Number Guide to Next-Day Availability Checks and Local Checks
For higher-value transactions, verify the number against an official directory. The American Bankers Association directs the public to an online lookup run by LexisNexis Risk Solutions, the official registrar of ABA routing numbers.3American Bankers Association. ABA Routing Number The Federal Reserve also runs a public routing number directory through its FedACH and Fedwire participant databases.4Federal Reserve Financial Services. E-Payments Routing Directory Either tool will confirm the name and location of the institution a nine-digit number points to before you commit the payment.