How many licks does it take to get to the Tootsie Roll center of a Tootsie Pop? That’s a question that candy lovers have been asking since 1970, when Tootsie Pop aired its first commercial that popularized the catchphrase. While the lollipop makers may have meant the query to be rhetorical, scientists have taken it upon themselves to find the answer in the decades since—and haven’t always agreed with one another’s results.
In 2015, scientists at New York University concluded that the answer was 1000. Before you cry foul, understand that these researchers weren't just looking to put a certain bespectacled owl out of work. Their study, which was published in the Journal of Fluid Mechanics in January 2015, was focused on how materials dissolve within a fluid flow, such as rocks in geological environments or pills for pharmaceutical applications ... or hard candy and saliva.
After modeling their process more generally, it wasn't hard to apply it to the age-old Tootsie Pop question. “Using that model, we can take an object of any size and kind of a typical flow speed that would be determined by how fast you lick candy, and then determine how long it would take for that to dissolve all the material away," applied mathematics professor Leif Ristroph, one of the study’s authors, told ABC News at the time.
The scientists didn't actually count literal licks (although they did get boxes of free lollipops from Tootsie Roll Industries when the company learned of the study) because they found it difficult to control the experiment in that case. “We started to test it, and it’s hard. Resisting the temptation to just bite into one is tough,” Ristroph admitted.
Ristroph and his team’s experiment wasn’t the first attempt to answer the burning question. A "licking machine" designed by Purdue engineering students averaged 341 licks to the center. A similar experiment at the University of Michigan landed on 411 as the magic number. Students at Bellarmine University in Louisville used human subjects and looked at additional factors such as gender and candy color to get to a final number; they found that an orange Tootsie Pop takes an average of 148 licks to consume, while a grape pop averages 198 licks. (You can view the full results of their study here.)
Ultimately, Tootsie Roll Industries may have gotten it right from the get-go when they declared that the world may never know the true answer after all.
A version of this story ran in 2015; it has been updated for 2022.