How Many Days Does It Really Take For a New Habit to Stick?

No, it doesn’t take 21 days to form a new habit.

New research, published earlier this year in the Proceedings of the National Academy of Sciences (PNAS) found that there is no set timeframe associated with habit forming.

While it is commonly believed that it takes three weeks (21 days) to create a habit, the timeframe may differ, depending on a variety of factors.

“You may have heard that it takes about 21 days to form a habit, but that estimate was not based on any science,” Colin Camerer, PhD, study author and behavioral economist at The California Institute of Technology, said in a news release.

“Our work supports the idea that the speed of habit formation differs according to the behavior in question and a variety of other factors.”

Here’s how timeframes to create habits may differ, and recommendations from experts on how to sustain new behaviors.