As much as we like to list specific qualities we’re looking for in a mate (responsible! funny! cute!), one of the most important ingredients is somewhat intangible, yet completely perceptible: chemistry.

Either you click or you don’t, and most adults have been on enough “meh” dates to know that all the good intentions in the world won’t salvage a couple that doesn’t have that all-important spark.

According to a recent survey, the majority of both men and women can tell 15 minutes into a date whether or not there’s chemistry. So if you think about the normal course of a date, by the time you’ve ordered drinks, or by the time the trailers start playing at a movie, you and your date probably already know whether there’s chemistry or not.

In other words, if you’re still excited about a date 15 minutes in, things are going well. If you are no longer excited, well, it’s probably not going to build up again.

Happily, lack of chemistry is not a total date dealbreaker: in fact, almost nothing is. Only 12% of Americans say they’d leave a date less than 30 minutes in. Most of us will stick it out, and hope to be pleasantly surprised by the end.