"Break the bank" is a slang term that means something costs too much money or exceeds the budget. This idiom has its origins in casino gambling as a reference to occasions when the casino bank does not have the cash to cover winning bets. In common usage, the phrase "break the bank" is often used as a way of saying that a service or product is too expensive.

When the phrase "break the bank" is used in common communications, one might expect to hear a phrase such as "Purchasing that car would break the bank." or a similar variation. In the majority of cases, the term is used in a derogatory manner to describe overpriced and expensive products. The phrase may also be used to warn others of impending costs or monetary loss on an acquisition in terms such as "Don't break the bank." Another variation of the phrase denotes that a price for goods is reasonable, and this is often expressed in statements such as "At this price, this purchase definitely won't break the bank."

While the phrase is commonly believed to originate with casino gambling, there are other variations on the origins of the phrase. Some obscure references point to the practice of storing money in ceramic banks, often called piggy banks. Early piggy banks did not have the removable plugs of modern piggy banks. The only way for people to retrieve their savings was to break the bank, so the individual's money often remained in the bank until times of unusual need. During times of economic hardship or unexpected expenses, these banks were often destroyed to retrieve the money. If one had broken the bank before times of need had truly arrived, the individual might not have enough money to carry him or her through a time of emergency.

While the phrase "break the bank" certainly did not originate with the 1948 game show of the same name, it has been commonly associated with this show as well. The original 1948 version of Break the Bank was hosted by Bert Parks and aired in 30-minute segments. The show saw later incarnations and revival of the phrase "break the bank" in 1976, 1985 and during the early 2000 era. In these quiz-style game shows, contestants answered questions for a chance to win money and were permitted to wager their earned winnings against a chance to win the larger prize by breaking the bank. During the time the show ran, no contestant ever broke the $250,000 US Dollar (USD) bank, and the closest contender was a dentist named Harry Duncan, who won $60,000 USD.