How Long Does It Really Take to Form a Habit?

Forming a habit is a classic life hack: You want to change something about your life, so you insert a new action into your daily routine. Soon enough, it becomes automatic—that’s the dream, anyway—and then that part of your life takes care of itself. So how long does it take to form a habit? Despite what you may have heard, it’s not necessarily 21 days.

The number of days it takes to form a new habit depends on the habit, on you, and on what strategies you’re using to build and maintain that habit. Scientific estimates have ranged from 21 days to eight months or more. Let’s look at why that range is so big, and what you can do to build habits faster.

The myth of the 21-day habit

The idea that a habit takes 21 days to form came from a surgeon, Maxwell Maltz, who observed that it seemed to take about three weeks for a person to get used to their new body after an operation like amputation or plastic surgery, James Clear writes. (Having gone through a few minor surgeries, I recall that it takes between two and three weeks for pain and swelling to subside enough that you aren’t constantly thinking about the fact you just had surgery; I have to wonder if that’s related.)

The surgeon’s idea was that it takes 21 days for people to dissolve and re-form a “mental image” of themselves. This isn’t backed by research; it’s just one guy’s gut feeling. But I think it stuck because it fits a lot of our experiences.

Let’s say you want to get up early to exercise first thing in the morning. Well, of course, you can do it once. But how do you make it a habit? When I was in that situation—becoming a morning exerciser despite not being a morning person—I made myself commit for a full week before I even allowed myself to complain about it or adjust my plan. I had to be up at 6:00 am every day, five days in a row, non-negotiable. I enjoyed having a break on the weekend, and then the second week was much easier. By the end of the third, this really was my new normal.

Even though the 21-day rule isn’t based on science, it’s a good timeframe for a ‘trial run’ of a new habit. After all, one day can be a fluke. One or two weeks is a timeframe we’ve been through before, and we can ride out a disruption to our normal life that long (imagine a holiday, or a week’s crunch time before a work deadline). But by the time you get to three weeks, or better yet, a full month, you’ve learned some things about your new habit and how it fits into your life. Even the simplest habits are never actually simple; you need to learn and practice a bunch of mini-skills in the process of building almost any habit.

So, by that 21-day mark, you’ve done the thing a bunch of times. Importantly, you’ve likely weathered a few interruptions or obstacles (like the weekend) and gotten back on track. It’s probably a good rule of thumb for a timeframe that is long enough to feel like “real life.” But that doesn’t mean it’s enough.

Research shows it takes months to make a habit automatic

Scientific research has attempted to measure how long it takes for a habit to truly become automatic. For example, this study asked participants to choose a habit and to attach it to something they did once a day (for example, “eat a piece of fruit with lunch”). The study lasted 12 weeks. Some of the participants felt their new habit was automatic after just a few weeks; many others weren’t there yet at the end of the study. The researchers concluded that most people would form an automatic habit anywhere between two and eight months…according to a model that they calculated would only apply to 62 per cent of the participants.

That’s a wide range, and we don’t know whether the other 38 per cent of people would have ever gotten to a point where the habit was automatic. The researchers also found that simpler habits (like drinking water) were quicker to become automatic than harder or more complex ones (like doing 50 situps).

A 2012 review looked at several other estimates and concluded that it would make more sense to tell people to expect at least 10 weeks for their new habit to become automatic, but also that it helps a lot just to know that any habit keeps getting easier the longer you do it.

Those authors point out that expecting a habit to form in 21 days can make people discouraged, and instead, it’s better to focus on the payoff of “working effortfully on a new behaviour for two to three months.”

Form habits faster with these strategies

Setting time-based commitments can be a helpful tool, like getting through the first week before changing the plan, or using your new moisturizer every day until the bottle is empty. However, another school of thought holds that long-term behaviour change is better described by “stages of change” than by calendar dates.

In some cases, a habit takes longer to form than you hope. But thinking this way means you may be able to get a habit to stick sooner than expected if you are intentional about the way you form the habit. Working consciously on your new habit can make it last longer, too, as we’ll see in the maintenance stage.

What to do in the first 21 days to make a habit stick

Your initial habit-forming period—whether you want to think of it as 21 days, or 30 days, or 66 days—is what behaviour change psychologists call the action stage. You’ve begun the habit, but it’s not automatic yet, and you might not be convinced that you’re really going to continue. In this stage, you can make your habit more likely to stick by doing the following:

• Remind yourself of your motivation to do it. For example, stick your reminder card for your next dentist’s appointment on your bathroom mirror, so that you remember not just that you should floss your teeth, but also why you want to floss your teeth.
• Restructure your environment to give you cues and support. For example, if you want to run every morning, set your shoes out the night before and have your spouse ask you how your run went when you return.
• Build self-efficacy by celebrating your small wins. This could mean checking off the days you did the thing on a calendar, but it could also involve working toward milestones (like total number of miles run) or making benchmarks of your progress (maybe you used to do your daily pushups with your hands on a chair, but now you can do them on the floor).
• Plan ahead for how you’ll maintain your habit even when you’re interrupted (more about that in a minute).

How to sustain a habit beyond those first 21 days

Once you’ve built some momentum, you’re in the maintenance stage. You’re doing the habit, and maybe it’s starting to feel automatic, or at least more of a part of your life than it used to be. In this stage, you may need to do some things like the following:

• Reevaluate your plan. Is running every morning still working for you? Maybe it makes more sense to make some of the runs longer and designate other days for rest, yoga, or strength training.
• Think ahead to obstacles you might face. If you go on a vacation, will you continue the habit? If you end up falling off the wagon for whatever reason, how will you get back into it?
• Make sure your motivation is something that will continue to work for you. For example, if you found it really motivating to keep up a streak on the calendar, the real test will come when you inevitably break your streak. At that point, there needs to be something other than the streak that is keeping you at it. This is often something intrinsic: You like being the person who flosses every day. You’re excited to sign up for a race with your running partner. You’re happy that your cholesterol is down from the way you’ve been eating.

Building a habit is not a matter of white-knuckling it until you hit a magic number of days. It’s a process that takes effort the whole time, even when you’re five years in. Habits are work, but the ones that last are the ones where the work feels worthwhile.