So-called free checking accounts are more expensive than ever, as the lumbering economy and new regulations squeeze bank revenues.

To avoid a monthly fee, bank customers in the U.S. must keep an average minimum balance of $723 in checking accounts that pay no interest—up 23% over last year, according to a new survey from data provider Bankrate Inc., which analyzed 477 checking accounts at 247 banks and thrifts. The average monthly fee on noninterest checking accounts rose 25% to $5.48, also a record.

Banks...