How Long It Actually Takes to Build a Habit

You have probably heard it takes 21 days to build a new habit.

If you have tried and failed around day 22, please know this.

The number was never actually true, and it may be part of why so many habits do not stick.

Where the 21 Day Myth Came From

This number did not come from habit research at all.

It traces back to a plastic surgeon in the 1960s who noticed his patients took about 21 days to adjust to changes in their appearance after surgery.

Somewhere along the way, this observation about physical recovery got turned into a rule about behavior change,

even though it was never studying habits in the first place.

What the Real Research Shows

A well known study followed participants trying to build a new daily habit,

like eating fruit or exercising, and found the actual average was 66 days, not 21.

Even more importantly, this was only an average.

Some people formed their habit in as little as 18 days, while others took as long as 254 days.

A newer, larger analysis published in 2025 reviewed 20 separate studies involving over 2,600 people and confirmed a similar pattern,

a median of 59 to 66 days,

with some habits taking as long as 335 days to fully stick.

Not All Habits Take the Same Amount of Time

Here is something worth knowing if you have felt discouraged.

Research has found that building an exercise habit takes about 1.5 times longer than building an eating or drinking habit.

In the original study, eating habits took a median of 59 days, drinking more water took 65 days, and exercise took 91 days.

This means if you have been trying to build a workout habit and it feels harder or slower than other changes you have made, that is not in your head.

It is a genuinely more complex habit to build, and it is expected to take longer.

Missing a Day Does Not Ruin It

This might be the most reassuring part.

Research has found that missing a single day here and there did not significantly affect someone’s ability to eventually form the habit.

Consistency over time matters far more than a perfect, unbroken streak.

What This Means for You

If you started a new habit a few weeks ago and it still feels effortful, that does not mean it is not working.

It likely means you are still in the middle of a process that research shows typically takes two to three months, not a few weeks.

Expecting a shorter timeline sets you up to feel like you have failed at something that was simply never going to happen that fast.

A Simple Way to Think About This

Instead of counting down to day 21, think in terms of about ten weeks.

Give any new habit that much time before deciding whether it is working for you.

And if you miss a day along the way, that is not the end of the habit.

It is simply part of a normal, human process.