How long does it take to form a habit?
On average, about 66 days. A 2010 University College London study found the median time for a new daily habit to become automatic was 66 days, with a range of 18 to 254 days. The popular “21 days” claim is a myth from a 1960 self-help book. Simple habits form faster, and doing them with another person helps you last long enough.
What the study found
- 96 participants each chose a new eating, drinking or exercise behavior to do daily in the same context.
- Median time to reach automaticity: 66 days.
- Range: 18 to 254 days.
- Missing one day did not materially affect the process.
- More complex habits, like exercise, took longer than simple ones, like drinking water.
Where “21 days” came from
In his 1960 book Psycho-Cybernetics, plastic surgeon Maxwell Maltz wrote that patients took “a minimum of about 21 days” to get used to a change. Over time, “a minimum of 21 days” became “21 days” and then a rule. It was never a measurement of habit formation.
How to make a habit form faster
- Make it tiny: two minutes is enough to start.
- Use the same cue every day: same time or right after the same action.
- Make it visible: a widget, a streak, a check-in someone else sees.
- Make it social: a friend doing it with you gets you through the week-three dip.
- Do not restart after a slip: just do it the next day.
DuoShare at a glance
- What it is
- An accountability habit tracker for iPhone: you and your friends check off goals and see when each other is done.
- Price
- Free. Goals, friends, streaks, reminders, the widget and challenges with up to 4 people cost nothing.
- DuoShare Pro
- Optional: groups and challenges of 5 to 10 people. $29.99 once, or $4.99 a month.
- Platform
- iPhone (iOS). No Android or web app yet.
- Challenges
- 7, 30 or 66 days, with one friend or a group, joined with one link.
- Streaks
- Your streak grows every day you check off a goal. Mark a goal N/A once a week without breaking it.
- Sharing
- Every milestone becomes a card you can post to Instagram, Messages or anywhere.
- Privacy
- Goals are private until you share them with friends you choose. Nothing is public. Your journal is never shared.
- Languages
- English and Spanish.
- Made by
- SearchWrite LLC, United States.
Start in under a minute
- Get DuoShare free on the App Store and sign up with your phone number.
- Add one to three small goals. Small sticks.
- Send a friend your invite link. Your streak starts with your first check-in.
iPhone · Free · No ads
Questions
How long does it take to break a bad habit?
There is less research on breaking habits, but the same principles apply: it usually takes weeks to months, and replacing the habit with a new routine works better than willpower alone.
Is it 21, 30 or 66 days?
The best evidence says 66 days on average, with a wide range. 21 days is a myth. 30 days is a good first milestone.
Does missing a day reset habit formation?
No. In Lally’s study, missing a single day did not significantly affect the habit forming.
What app helps you form a habit in 66 days?
DuoShare has built-in 66-day challenges you can do with a friend, free on iPhone.