Guide · Habits
How long does it take to break a habit? What the research really says
You have probably heard that it takes 21 days to break a habit. It is a tidy number, and it is not what the research found. The best-known study puts the average at about 66 days for a new habit to feel automatic, with a range so wide that "it depends" is the honest answer. Here is what the studies say, why the 21-day idea stuck, how breaking a habit differs from building one, and a simple 10-week plan.
Photo is illustrative, not from a past month. Credits.
Quick answer. There is no fixed number. In the best-known study, led by Phillippa Lally at University College London and published in 2010, a new daily habit took an average of about 66 days to become as automatic as it was going to get, ranging from 18 days to a predicted 254 days. A 2024 review of 20 studies with 2,601 people found median times of 59 to 66 days and average times of 106 to 154 days. Breaking an old habit works best by replacing it: change the cue, put a new action in the old slot, and repeat it daily. Missing one day did not undo progress. Plan for two to three months, not three weeks.
Every January, a great many people start something new and give it three weeks. When it still feels hard on day 22, many decide they have failed. They have not. They have simply been given the wrong number.
This guide is about the right one, or rather the honest range, and about what actually helps a habit stick, or an old one fade.
The short version
- About 66 days on average for a new daily habit to feel automatic, in the best-known study. Some people got there in 18 days; for others the model predicted 254.
- A 2024 review of 20 studies (2,601 people) found medians of 59 to 66 days and averages of 106 to 154 days.
- 21 days is a myth, or at best a minimum that got rounded into a rule.
- One missed day does not reset you. Repeated misses do slow things down.
- Simple habits come faster. In Lally's study, exercise took about one and a half times as long as eating or drinking habits.
- To break a habit, replace it. Same cue, new action, repeated daily.
What the research says
The study everyone quotes was run at University College London by Phillippa Lally and colleagues and published in the European Journal of Social Psychology in 2010. They recruited 96 volunteers. Each chose one new daily behaviour, such as eating a piece of fruit with lunch, drinking a glass of water or going for a short run, tied to something they already did every day. Every day for 12 weeks, they rated how automatic it felt.
The result, as the British Psychological Society's Research Digest summarises it: "The average time to reach maximum automaticity was 66 days." The spread was huge, "from 18 days to a predicted 254 days". Some people were still far from that point when the 84 days ended, so their times were projected, not observed.
In a University of Surrey interview in January 2026, Dr Lally put it plainly: "The average time it took for the participants in my study to form a daily habit was 66 days," and "the range was 18 to 254 days."
A 2024 systematic review and meta-analysis by Ben Singh and colleagues in the journal Healthcare pulled together 20 studies with 2,601 participants. In the four that reported a time, medians ranged from 59 to 66 days and means from 106 to 154 days, with individual times from 4 to 335 days. Habits done in the morning, and habits people chose for themselves, tended to be stronger. The authors are honest that the evidence is limited: most of the studies had a high risk of bias. Their conclusion is a fair one to live by: habits can start to form in about two months, but people differ a lot.
Where the 21-day idea came from
The 21 days usually goes back to Maxwell Maltz, a plastic surgeon, whose 1960 book Psycho-Cybernetics described people taking a minimum of about 21 days to get used to a change, such as a new face in the mirror. It was an observation from his practice, not a study of habits. Over the years "a minimum of about 21 days" became "21 days", and then a promise. The trouble with the promise is what it does on day 22: if it still feels like effort, you think you are doing it wrong.
A better way to think about it: three weeks is often when a new habit stops feeling strange. Two to three months is often when it stops needing a decision.
Breaking a habit vs forming a new one
Most of the research measures how long it takes to build a habit. Breaking one is less studied, but the two are closely linked. A habit is a cue (a time, a place, a feeling, a person) followed by an action you no longer think about. You rarely delete the cue: 6pm still comes, the sofa is still there, the stressful email still arrives. What you can do is put something else in that slot, again and again, until the new action is the automatic one.
That is why "stop doing X" plans are hard, and "when X happens, I do Y instead" plans work better. The old habit fades as the new one grows. It may still knock now and then, especially when you are tired or somewhere new. That does not mean you are back at the start.
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Why some habits take longer
- Effort. In Lally's study, exercise took about one and a half times as long to plateau as eating or drinking habits. A glass of water is easier to make automatic than a run.
- How often. A daily habit gets more practice than a weekly one. A Friday-night habit gets only four or five repeats a month, so expect it to take longer.
- A clear cue. "After my morning coffee" works better than "sometime in the day". Dr Lally's own advice: "if you make a clear plan of when and where you will do something you are more likely to do it."
- Choice. The 2024 review found habits people chose for themselves tended to be stronger than ones set for them.
- Reward and mood. Habits you enjoy, or that bring quick relief, grow fast. That is also why old ones can be stubborn.
How to break a habit: 8 steps that fit the research
- Pick one habit, not five. Changing sleep, food, drink and screens all at once on 1 January is why many plans fall over by the 10th.
- Find the cue. For three days, notice when the habit happens: the time, the place, who is there, how you feel. Writing it down helps; these journaling prompts make it easier.
- Choose the replacement. Something you can do in the same moment: a walk instead of the after-work drink, a book instead of the phone in bed.
- Write an "if, then" line. "If it is 6pm and I walk in the door, then I make a pot of tea and change my clothes."
- Change the room. Make the old habit a little harder and the new one easier: the phone charges in the kitchen, the running shoes sit by the door.
- Repeat it daily, in the same slot. Repetition in a stable context is what the studies measured.
- Don't panic over one miss. The BPS summary of Lally's study: "a single missed day had little impact on later automaticity gains." Just do it the next day.
- Count in weeks, not days. Check in at week 3, week 6 and week 10, and ask: does this need less thought than it did?
A 10-week plan
| When | What to do | What it usually feels like |
|---|---|---|
| Days 1-3 | Notice the cue. Write the "if, then" line. Change one thing in the room. | Easy. Motivation is high. |
| Weeks 1-3 | Do the replacement every day in the same slot. | The hardest stretch. The old habit still pulls. |
| Weeks 4-6 | Keep the slot. Add a second small cue if one time of day is still hard. | Less strange. Some days you forget you used to do it. |
| Weeks 7-10 | Test it gently: a busy week, a trip, a late night. Restart the next day if you slip. | Around the 66-day average: for many people it needs less thought now. |
| After week 10 | Keep the cue and the room as they are. Pick the next habit, if you want one. | For some it is settled; for others it takes months longer. Both are normal. |
Drinking, smoking and vaping
Many people searching this question are thinking of a drink, a cigarette or a vape. The habit steps above still help, but these are not only habits: alcohol and nicotine act on the body, and stopping can bring cravings and physical effects for a while.
- If you drink heavily or every day, do not stop suddenly on your own. Stopping suddenly can be dangerous. Talk to your doctor first about a safe plan.
- For smoking and vaping, your doctor or pharmacist can tell you about free stop-smoking support where you live; you don't have to do it on willpower alone.
- If it feels like more than a habit, or anything feels urgent, call your local emergency number or find a free helpline at findahelpline.com.
For the evening drink specifically, my guides on what to do instead of drinking, what to drink instead and what happens in a month without alcohol go into detail. If you would rather cut down than stop, see how to drink less without quitting.
Is a month long enough?
Honestly: a month is a strong start, not the finish line. The research average is a little over two months. But the first weeks are the hardest part, and a month where the new routine is built into every day gives the habit a lot of clean repeats in a stable setting, which is exactly what the studies measured. After that, the work is keeping the cue and the slot when normal life comes back. My guide to keeping the good bits after a sober month is about that part, and how to reset your life in 30 days lays the month out week by week.
Where The Quiet Month fits
I built The Quiet Month around a small set of daily habits: wake at a similar time, move every day, eat proper meals, sit quietly for a few minutes, talk in the evening, sleep at a sensible hour. It runs for a whole month, for up to four guests, each in their own private flat a short walk from me. The month has one firm rule: no alcohol, no smoking, no drugs, for everyone, me included. That makes the first, hardest weeks of a new habit a lot simpler.
Honestly: I'm self-taught, not a doctor or counsellor. The Quiet Month is not medical and not therapy. Every guest is 21 or over and brings a doctor's fit-to-join letter and travel insurance. I don't publish where I am; after a free video call, if we both want to go ahead, you learn the country and city before you sign anything, and nothing is paid before that call and a signed agreement. The programme fee is US$10,000 for the month; your flat and flights are extra. See the dates, the price page and what a month looks like.
Email me first at info@thequietmonth.com, start step 1 of the application (about five minutes, free, no commitment), or book a free 20-minute call.
The Quiet Month team
Questions people ask
How long does it take to break a habit?
There is no fixed number. In the best-known study (Lally and colleagues, University College London, 2010), a new daily habit took an average of about 66 days to feel automatic, ranging from 18 days to a predicted 254. Breaking an old habit usually means building a new one in its place, so plan for two to three months rather than three weeks.
Does it really take 21 days to form a habit?
No. The 21-day idea is usually traced to Maxwell Maltz's 1960 book Psycho-Cybernetics, which described people taking a minimum of about 21 days to adjust to a change. Later research found an average of about 66 days, with very wide differences between people.
What happens if I miss a day?
Very little. In Lally's study, a single missed day had little impact on how the habit formed over time. Repeated misses do slow it down, so the rule is simple: don't miss twice if you can help it, and pick it up again the next day.
Why do some habits take longer than others?
Effort, frequency and the cue matter. In Lally's study, exercise took about one and a half times as long as eating or drinking habits. Daily habits get more practice than weekly ones, and a clear "when and where" plan helps. A 2024 review also found that habits people chose themselves, and morning habits, tended to be stronger.
How long does it take to break a drinking habit?
It varies from person to person, and alcohol is not only a habit: it acts on the body. Replacing the evening drink with something else in the same slot helps. If you drink heavily or every day, talk to your doctor before stopping, because stopping suddenly can be dangerous.
Sources
- Lally, van Jaarsveld, Potts and Wardle (2010), European Journal of Social Psychology 40(6): How are habits formed: Modelling habit formation in the real world (the original study)
- BPS Research Digest: How to form a habit (summary of Lally et al.) (96 recruited, 82 completed; average 66 days to maximum automaticity; 18 days to a predicted 254; one missed day had little impact; exercise about 1.5 times as long; read 29 Oct 2026)
- University of Surrey (21 Jan 2026): Does it really take 66 days to form a habit? We asked expert Dr Pippa Lally (66 days average, range 18 to 254; plan when and where; read 29 Oct 2026)
- Singh B, Murphy A, Maher C, Smith AE (2024), Healthcare 12(23):2488: Time to Form a Habit: A Systematic Review and Meta-Analysis of Health Behaviour Habit Formation and Its Determinants (20 studies, 2,601 participants; medians 59 to 66 days, means 106 to 154 days; read 29 Oct 2026)
- Find A Helpline: free helplines in many countries
Prices and facts were checked on 29 October 2026. Prices change; always check the source before you book anything.