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21/90 Rule – How Long Does It Take to Form a Habit

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Have you heard that it takes 21 days to form a habit? But is that correct? Have you tried to implement good habits for 21 days straight but then returned to your old ways? Maybe the 21/90 rule will work better for you. And how long does it take to form a habit for real?

21/90 Rule - How long does it take to form a habit

Your brain likes habits. They’re efficient. Once a behavior becomes a habit, your brain doesn’t have to think about it anymore. This is why it can be hard to break bad habits but easy to maintain good ones – your brain is just doing what it knows.

Building habits that stick take time. Because you need to unlearn a behavior that is already automated and replace it with a new one.

The good news is that it’s definitely doable. But how long does it take? Are 21 days enough? And what does the 21/90 rule has to do with it?

Disclaimer: Please note that I’m not a mental health expert; these are just a few tips that might help you form a new habit and get rid of unwanted ones. If you have an addiction, please turn to a mental health professional. 

What is the 21/90 Rule

When it comes to habit-forming, The 21/90 rule states that it takes 21 days to make a habit and 90 days to make it a permanent lifestyle change.

This means you need to do something consistently for 21 days until it becomes a habit. And once it’s become a habit, you need to keep up the good work for up to 90 days until the change is permanent and has become part of your lifestyle.

Does it take 21 days to form a habit?

The answer is no.

According to a study by Philippa Lally and her research team from University College London, it can take anywhere from 18 to 254 days to form a new habit- which averages out to about 66 days for a new behavior to become automatic.

Habit formation is a gradual process that takes time. The 21/90 rule is actually more of a guideline than an absolute rule.

So if you try something for a few weeks and you’re making progress, but the habit doesn’t stick, don’t give up. Remember that it takes time and keep going.

So why does the 21-day rule exist?

The 21-day rule likely came from a plastic surgeon named Maxwell Maltz. In the 1960s, he wrote a book called Psycho-Cybernetics in which he claimed, “[It takes] a minimum of 21 days for an old mental image to dissolve and a new one to jell.”

He noticed that was the case, whether the patient had had a leg amputation or a nose job. But this was just an estimate based on his observations, not an actual scientific study.

More recent research has shown that this very simple rule isn’t always the case, and the adjustment period to new behaviors can take much longer.

So how long does it actually take to form a habit?

So how long does it actually take to make a habit stick? Well, that depends.

Phillippa Lally – a health psychology researcher at University College London – and her research team looked at 96 people trying to form new habits over the course of 12 weeks.

They found (and published in the European Journal of Social Psychology) that it took anywhere from 18 to 254 days for a new behavior to become automatic – with an average of 66 days.

Of course, this study supported habit formation, but the key intake is that it takes time (up to 254 days which is more than eight months). So if you’re trying to form a new habit, don’t give up after 21 days if it doesn’t become automatic yet.

Anyone can do something for three weeks. Because it’s almost like a challenge. But the wrong mindset is: “I can do this for 21 days, and that’s it.” The right attitude is: “I will keep doing this until it becomes a habit.”

So, if you’re trying to form habits, make new year’s resolutions, or totally overcome a bad habit, be patient and give it time. It won’t happen overnight. But eventually, if you keep at it, the routine will become automatic.

And even though there’s no exact science backing up the 21/90 rule, that doesn’t mean it can’t be helpful.

If someone would tell you, you’ll need to do something for two to three months (or even longer), it might seem like a daunting task, and you might be less likely to stick to it.

However, breaking that timeline down into smaller goals- like 21 days – can seem more manageable.

And once you’ve done it for 21 days, you might be more likely to keep going on up to 90 days. And after 90 days, you’re already so used to it that it could become your second nature.

And if you don’t feel completely secure about the new habit creation after 90 days, just continue until you do.

10 tips to help you form a new habit using the 21/90 rule

So, if you’re ready to start making fantastic decisions and replace the old habits with new ones that serve you better, here are 10 tips to help you form good habits (and a better life) using the 21/90 rule:

1. Habit loop: Become aware of your current habits

The first step is always awareness. You need to become aware of your current good and bad habits.

And this is when the concept of the habit loop is helpful.

The habit loop is simply the cue (trigger), routine (behavior), and reward.

  • Cue: This trigger tells your brain to go into autopilot and start the habit.
  • Routine: This is the actual habit itself.
  • Reward: This is what you get from making the habit. It reinforces the behavior so that your brain will want to do it again in the future.

For example, let’s say you always have a doughnut with your coffee in the morning.

  • The cue is the time of day (around 10 am) and/or the location (in front of the coffee machine).
  • The routine is eating the doughnut.
  • And the reward is the sugar rush that comes from eating it.

Now that you’re aware of your current habits, what triggers lead to the bad habits? What is the routine/habit/action itself? And what are the rewards that keep you coming back for more?

Only when you become aware of your current situation can you change it.

2. Set a realistic goal & start with something small

If you want to change something major in your life, don’t try to do it all at once.

What are the smallest possible steps and changes you can make that will get you closer to your big goal?

And set a realistic personal or professional goal. Something challenging enough to motivate you, but not too difficult that you feel overwhelmed.

3. Find your “why.”

Before you start, it’s essential to know your “why.”

  • Why do you want to make this change?
  • What is your motivation?

When you clearly understand your “why,” it will be easier to stay on track.

Also, make sure your “why” is aligned with your personal values.

RELATED POST: Core values – 150+ examples of personal core values + Core values list PDFs

4. Visualize yourself achieving your goal

This is an important step that very few people do. Once you know your why and what your goal is, it’s time to visualize yourself achieving it.

  • What does your life look like after you’ve made the change?
  • What do you see around you?
  • What do you see in the mirror?

And continue a bit further.

Think of how people would talk to you and about you. How would that new life make you feel? Use all of your senses to create a clear image in your mind.

And the better and more detailed you can visualize it, the better.

5. Make a plan

Once you know your “why,” it’s time to make a plan. What are the specific steps you need to take to reach your goal?

Write down your plan.

What are the habits you want to form? How will you make time for this?

6. Use habit stacking

Now that you’ve established your goal, you know your “why,” and you can see yourself achieving it, it’s time to start building your habits.

One of the best ways to add healthy habits to your current life is habit stacking. This means combining your new habit with an existing practice already part of your routine.

Let’s say you want to read 10 pages of an inspiring book in the morning. So, why not combine it with your morning coffee?

The coffee would then become the habit trigger: after a while of continuously and consciously combining those two would make the coffee always trigger the will to read the book.

7. The Seinfeld Strategy

The Seinfeld Method - Seinfeld Calendar
“Don’t break the chain” – The Seinfeld Strategy

“Don’t break the chain” is the core of one popular method of habit development. It’s called the The Seinfeld Strategy.

The amazing comedian Jerry Seinfeld came up with this method to write jokes every day, and it’s a great way to develop any habit. All you need is a wall calendar and a red pen.

The calendar must be placed somewhere within sight of where you’ll implement your new habit. And every day that you complete that same habit, you get to put a big red X on that day. The goal is to never break the chain of Xs.

The longer the chain, the more motivated you’ll be to keep going.

RELATED POST: The Seinfeld Strategy – The Simplest Way to Build Habits

Related post: Grab a printable calendar, print it out, place on the wall and mark those Xs:

Cute & Free Printable SaturdayGift Calendars

Cute & Free Printable November Monthly Calendars Featured Collage Image
Examples of SaturdayGift calendar designs

Looking for some habit tracker printables? You can find multiple pretty ones from this post: 43 cute & free habit tracker printables

Monthly habit tracker
Habit tracker printables

8. Make it a routine

One of the best ways to form a new habit is to make it a part of your daily routine. If you can, try to make your new habit at the same time every day. Set a reminder if you need to.

9. Don’t give up if you miss a day

It’s important to remember that it’s progress not perfection that counts. If you miss a day, don’t give up; just get back on track immediately the next day.

After you’re back on track, this is also an excellent place to reflect and develop strategies to prevent falling off the wagon again.

The same researchers that discovered that habits take anywhere between 18 to 254 days to form also found that losing a day had little effect on the habit formation process.

Focus on progress not perfection - Bill Phillips - Perfectionism Quotes
“Focus on progress not perfection” -Bill Phillips

10. Reward yourself

Reward yourself with something you enjoy when you reach a milestone or accomplish something on your goal list. This will help keep you motivated and encouraged along the way.

Optional: Find an accountability partner or group

An accountability partner, a group, or a habit coach can be a great way to help you build permanent habits, stay on track and achieve your goals. So if you feel like you need help, find someone who will support you, encourage you, and hold you accountable.

Why it can be challenging to break a habit

Breaking bad habits can be difficult for many reasons. It can be hard to change something you’ve been doing for a long time. And it’s easy to fall back into your old ways when you’re under stress or facing a challenging situation.

It’s because the bad habit might have served you at the time. Maybe you were stressed and on the verge of a burn-out at the time. And the only way you knew how to relax and get your mind out of work was to binge-watch Netflix.

But then you just kept on binge-watching… night after night. And now that habit doesn’t serve you anymore, but it’s taking away from something more important like sleep.

It can be difficult to break habits because they’ve become a part of your daily routine and even who you are. But it’s important to remember that you’re not your habits. You can change, and you have the power to choose which habits will define you.

Breaking habits requires unlearning. This means letting go of the old routine and replacing it with a new one.

It can be helpful to think of it as rewiring your brain. The old habit is like a well-worn path in your brain, and the new practice is like a new path that you’re creating.

Creating this new path takes time and effort, and it won’t happen overnight. But with time and practice, the new habit will become second nature.

Read more about how to break a habit from this post: How to break a habit (& how long does it take)

So that’s about it – The 21/90 Rule in a nutshell. Follow these tips, and you’ll be well on your way to forming habits that will last a lifetime.


What’s the 21 90 rule?

The 21/90 rule states that it takes 21 days to make a habit and 90 days to make it a permanent lifestyle change. If you want to start making positive changes in your life, set a goal and then work towards it 21 days and continue for up to 90 days.

Is it true it takes 21 days to form a habit?

It’s a common belief that it takes 21 days to form a habit, but that’s not actually true. According to this study published in European Journal of Social Psychology, it can take anywhere from 18 to 254 days to develop new habits – the average being 66 days. However, this number can vary depending on the person and the goal they’re trying to achieve.

How long does it take to make a habit routine?

The research states it can take anywhere from 18 to 254 days to form a habit routine – the average is about 66 days.

Can you form a habit in 7 days?

7 days is too short a time to form a habit that’ll stick. The research states it can take anywhere from 18 to 254 days to form new habits (averaging 66 days).

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