Cravings, habits & relapse

How long does it take to break a habit?

Reviewed September 13, 2026 · 6 sources · Jump to sources

Short answer

There's no proven timeline for breaking a habit, but the best evidence points to months, not 21 days. In a key study (Lally et al., 2010), a new daily eating, water-drinking or exercise habit took a median of 66 days to become automatic, ranging from 18 to 254 days. That study measured forming habits, not ending them, and researchers say breaking an existing habit takes more effortful strategies.

Key takeaways

In Lally et al. (2010), new daily habits took a median of 66 days to become automatic.
Individual times ranged from 18 to 254 days, so slower progress is normal.
The 21-day rule appears to come from anecdotes about plastic surgery patients, not habit research.
Breaking an existing habit takes more effortful strategies than building a new one.
In the habit-building research, missing one day didn't seriously set progress back.

What did the 66-day study actually find?

The number most people quote comes from a 2010 paper by Lally and colleagues in the European Journal of Social Psychology. Participants repeated a healthy eating, water-drinking or exercise behavior, and the median time to reach 95% automaticity was 66 days. Individual results ranged from 18 to 254 days, with considerable variation across people and behaviors.

A 2024 systematic review of habit-formation studies found a similar picture: median times of 59 to 66 days, and individual times anywhere from 4 to 335 days. Researchers at University College London suggest telling people to expect a habit built on daily repetition to take around 10 weeks.

Where does the 21-day rule come from?

Not from habit research. The 2024 review traces the idea to Maxwell Maltz's book Psycho-Cybernetics and notes that the timeline has been questioned, because the time needed is thought to differ by behavior and by person. The University College London researchers go further and call it a myth that appears to come from anecdotal evidence about plastic surgery patients who adjusted psychologically to their new appearance within 21 days.

So there's no reason to expect a habit to be gone after three weeks, or to feel you've failed if it isn't.

Is breaking a habit different from building one?

Yes, and the evidence is thinner. In psychology, habits are actions triggered automatically by contextual cues that have become linked to them. The University College London team points out that it is not possible to form a habit for not doing something, and that breaking an existing habit requires different and more effortful strategies than making a new one. The 2024 review also excluded studies aimed at stopping behaviors such as smoking, so its timelines don't directly tell you how long quitting takes.

Guidance for smokers describes the change in terms of those links: each time you resist an urge and choose something else, Victoria's Better Health Channel says, you're helping your brain break the link between the activity and the cigarette.

What does this mean if you're quitting something?

Use the research as a guide to expectations, not a deadline.

Plan for months, not weeks, and judge progress by the overall trend rather than a single day.
One slip isn't a reset. In the habit-building research, missing a single opportunity didn't seriously impair progress, and gains soon resumed.
Know your cues. Because habits are triggered by cues, notice what tends to come right before the old behavior and have a replacement ready.
Treat cravings as their own challenge. For nicotine, the NHS says cravings are hardest in the first 28 days and that a single craving usually lasts only a few minutes.

How Vow can help

Vow builds a personalized quit plan from your triggers, toughest times and reason for quitting, then tracks your streak, money saved and daily check-ins over the weeks and months it takes. If you slip, it's logged without shame: your best streak is kept and a fresh run starts.

Sources

Each source below was read when this answer was reviewed. Open a source to see the passages the answer relies on.

PubMed Central — Singh et al. (2024), Time to Form a Habit: A Systematic Review and Meta-Analysis of Health Behaviour Habit Formation and Its Determinants (reference list)pmc.ncbi.nlm.nih.gov
Lally P., van Jaarsveld C.H.M., Potts H.W.W., Wardle J. How are habits formed: Modelling habit formation in the real world. Eur. J. Soc. Psychol. 2010;40:998–1009. doi: 10.1002/ejsp.674.
Lally et al. examined the formation of healthy eating, water consumption or exercise habits and reported that the median time to reach 95% automaticity was 66 days (range: 18 to 254 days).
Four studies reported the median or mean times to reach habit formation, ranging from 59–66 days (median) and 106–154 days (means), with substantial individual variability (4–335 days).
A widely cited idea in popular culture, stemming from the book Psycho-Cybernetics by Maxwell Maltz, suggests that new habits can be formed with just 21 days of repetition.
However, this proposed timeline has been questioned, and the period necessary for the establishment of habits is thought to differ based on factors such as the specific behaviour and the individual.
aimed at ceasing a non-virtuous health-related behaviour, i.e., smoking or reducing social media use, were deemed ineligible.
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PubMed Central — Gardner, Lally & Wardle, Making health habitual: the psychology of 'habit-formation' and general practicepmc.ncbi.nlm.nih.gov
More relevant research found that automaticity plateaued on average around 66 days after the first daily performance, although there was considerable variation across participants and behaviours.
Health Behaviour Research Centre, Department of Epidemiology and Public Health, University College London, London
Therefore, it may be helpful to tell patients to expect habit formation (based on daily repetition) to take around 10 weeks.
This myth appears to have originated from anecdotal evidence of patients who had received plastic surgery treatment and typically adjusted psychologically to their new appearance within 21 days.
Within psychology, 'habits' are defined as actions that are triggered automatically in response to contextual cues that have been associated with their performance
it is not possible to form a habit for not doing something
The automaticity of habit means that breaking existing habits requires different and altogether more effortful strategies than making new habits.
Missing the occasional opportunity to perform the behaviour did not seriously impair the habit formation process: automaticity gains soon resumed after one missed performance.
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Better Health Channel (Victoria State Government) — What to expect when you quit smokingbetterhealth.vic.gov.au
you're helping your brain break that link between the activity and the cigarette.
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NHS Better Health — Understand your smoking triggers and cravingsnhs.uk
Cravings are hardest in the first 28 days as your body adjusts to no nicotine. After that, they often start to get easier.
Cravings usually only last a few minutes, so have a distraction ready.
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MedlinePlus Medical Encyclopedia — How to stop drinkingmedlineplus.gov
If you have withdrawal symptoms, such as trembling hands, when you go without alcohol, you should not try to quit on your own.
It may be life threatening.
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NHS — Alcohol supportnhs.uk
If you have become physically dependent and need to stop drinking completely, stopping overnight could be harmful.
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This page is general information, not medical advice, and it does not replace care from a qualified professional. If you are in immediate danger, call your local emergency number. Vow is not a medical service.