How many times have you heard that you need to do something for 40 days before it becomes a habit? Or is it 21 days? Or two weeks? Or 70 days? 100?

There’s a lot of conflicting information out there, but the general message is this: there’s a ‘magic number’ for how long you need to persist with a task to transform it into a routine that sticks. If you can just reach that magic number, we’re told, you’ve done it. The habit is set.

But that might be all wrong, at least according to a new study.

Researchers found that how long it takes to form a habit depends on a bunch of different factors, including what the habit actually is. Getting into the habit of going to the gym, for example, took an average of – brace yourselves – six months. To form the habit of hand-washing, however, required just a few weeks.

There’s no ‘magic number’ for forming a new habit, says study