It doesn’t take much to upend many Americans’ finances. A car that won’t start, a furnace that dies or a trip to the hospital can leave households struggling to make ends meet.

According to the Federal Reserve, 44 percent of U.S. adults say they would have trouble coming up with $400 to cover an unexpected expense. Even families who have more in the bank can flounder. Surveys by The Pew Charitable Trusts found that 51 percent of families with at least $2,000 in savings reported trouble paying the bills after a financial shock.

Yet it is hardly a shock if an appliance wears out or a car breaks down.

It’s time to rethink what we mean by unexpected expenses. In my latest for the Associated Press, how to predict surprise bills without a crystal ball.