ABA routing number checker

A US routing number is nine digits, and the ninth is a check digit computed from the other eight. Multiply the digits in order by 3, 7, 1, 3, 7, 1, 3, 7, 1, add the results, and a genuine number divides exactly by ten.

The first two digits also carry meaning: they identify the Federal Reserve district that processes the routing, which is why a number beginning 02 belongs to a New York institution and one beginning 12 to a San Francisco one.

Routing numbers are public

Every bank publishes its routing numbers, and they are printed along the bottom of every cheque. There is nothing to protect. Your account number is the sensitive half, and the pair together is enough for someone to attempt an ACH debit.

That is the practical point: a caller who already knows the routing number and wants "just the account number to verify" is asking for the only piece they are missing. Nobody with a legitimate reason to move money needs you to read it out to them.

Common places this matters

• Direct deposit forms sent by a new employer who contacted you first. Payroll redirection fraud starts exactly here.
• Rental deposits where the listing was copied from a real property and the bank details are the only thing changed.
• Invoices with updated details. Ring the supplier on a number you already had, never one on the new invoice.