How Long Does It Take to Break a Habit?

Quick Answer

66 days on average, according to the most rigorous research available. A 2009 study by Phillippa Lally and colleagues at University College London found that forming (or breaking) a habit took anywhere from 18 to 254 days, with a median of 66 days. The often-quoted "21 days to break a habit" has no scientific basis — it originated from a misinterpretation of a 1960 observation by plastic surgeon Maxwell Maltz.

The Science Behind the Numbers

The Lally 2009 Study

Published in the European Journal of Social Psychology, this study tracked 96 participants over 12 weeks as they tried to adopt a new daily behavior. Key findings:

• The range was enormous: 18–254 days to reach automaticity (the point where the behavior feels automatic)
• The average was 66 days
• Simple habits (drinking a glass of water with lunch) formed faster than complex ones (doing 50 sit-ups before dinner)
• Missing a single day did not reset progress — occasional lapses had negligible impact on habit formation

The Habit Loop

Charles Duhigg, in "The Power of Habit," popularized the neurological habit loop identified by MIT researchers:

1. Cue — a trigger that initiates the behavior (stress, boredom, a specific time of day)
2. Routine — the habitual behavior itself (smoking, snacking, nail-biting)
3. Reward — the payoff your brain receives (dopamine release, stress relief, satisfaction)

Breaking a habit requires disrupting this loop — typically by identifying the cue, replacing the routine, and finding an alternative reward.

How Long to Break Specific Habits

Habit	Typical Duration to Break	Difficulty Level
Nail biting	1–3 months	Moderate
Checking phone first thing	2–4 weeks	Low–Moderate
Snacking when bored	1–3 months	Moderate
Smoking	3–12 months (with relapses)	Very High
Excessive social media use	1–2 months	Moderate
Procrastination patterns	2–6 months	High
Stress eating	2–4 months	High
Staying up too late	2–6 weeks	Moderate
Negative self-talk	3–6 months	High
Excessive caffeine	1–3 weeks (physical), 1–2 months (behavioral)	Moderate

These are estimates based on clinical observations and habit research. Individual experiences vary widely.

Why "21 Days" Is a Myth

The 21-day claim traces back to Dr. Maxwell Maltz's 1960 book "Psycho-Cybernetics." Maltz, a plastic surgeon, observed that amputees took a minimum of about 21 days to adjust to the loss of a limb. He wrote: "These, and many other commonly observed phenomena, tend to show that it requires a minimum of about 21 days for an old mental image to dissolve."

Note the word "minimum." Self-help authors later stripped the nuance and turned it into a definitive "21 days to form or break any habit." The Lally study showed this is far too optimistic for most behaviors.

Strategies That Work

Identify Your Triggers

Keep a log for one week. Every time you engage in the habit, write down:

• What you were doing
• What time it was
• How you were feeling
• Who you were with

Patterns will emerge. Most habits have 1–3 primary triggers.

Replace, Don't Eliminate

Your brain craves the reward. Trying to eliminate a habit without providing an alternative reward usually fails. Instead:

• Smoking — replace with nicotine gum, deep breathing, or a short walk
• Stress eating — replace with a 5-minute stretch, herbal tea, or calling a friend
• Phone scrolling — replace with reading a book, journaling, or a puzzle app

Use Implementation Intentions

Research by psychologist Peter Gollwitzer shows that "if–then" plans dramatically improve behavior change success:

• "If I feel the urge to snack at 3 PM, then I will take a 10-minute walk."
• "If I reach for my phone in bed, then I will pick up my book instead."

Leverage Your Environment

• Remove cues: Don't keep cigarettes in the house, move junk food out of sight, charge your phone in another room
• Add friction: Make the habit harder to do (delete social media apps so you have to use a browser)
• Reduce friction for replacements: Put the book on your pillow, keep walking shoes by the door

Expect and Plan for Lapses

The Lally study's most reassuring finding was that missing one day did not significantly affect habit formation. Perfection is not required. What matters is getting back on track quickly after a slip, not achieving a flawless streak.