How to Dunk an Oreo, According to Science

Dunking an Oreo in a glass of milk might seem like a matter of taste—or just a way to pass time—but as it turns out, there’s actual science behind the perfect dunk. And yes, there’s even a magic number.

According to researchers at Utah State University’s Splash Lab, the ideal Oreo dunk time in skim milk is three seconds.

The lab’s findings, first reported by Mental Floss, came from a 2016 experiment where engineers tested how quickly an Oreo absorbs milk. In just one second, an Oreo soaks up about 50 percent of the liquid it’s capable of holding. After two seconds, it hits 80 percent. By the four-second mark, the cookie has absorbed all the milk it can—so any longer doesn’t add much, except mess.

Wait too long, though, and you’ll be fishing cookie crumbs from the bottom of your glass. If left dunked for five minutes, a standard Oreo in skim milk will completely lose its structure and dissolve.

For fans of a longer soak, there is a workaround. Try using whole milk or heavy cream. The higher fat content slows down the absorption process, giving you more time to dunk without losing the cookie to the depths.

So, whether you’re a quick dipper or a slow soaker, now you know: dunking Oreos isn’t just delicious—it’s physics.