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Habit formation calculator

Not 21 days. Pick your start date and see when a habit tends to feel automatic, as a range, with the study’s dates on your calendar.

  • Free
  • Runs in your browser
  • Nothing is saved or sent

Day 1 is the first day you do it.

Pick a date to see your timeline.

Missing a day now and then didn’t reset progress in the study. It’s a range, not a deadline.

Your timeline

  1. 77-day milestone
  2. 1414-day milestone
  3. 18Fastest in the study
  4. 2121-day milestone
  5. 3030-day milestone
  6. 5050-day milestone
  7. 66Median in the study
  8. 100100-day milestone
  9. 180180-day milestone
  10. 254Slowest in the study
  11. 365365-day milestone

Study: Lally et al., 2010, European Journal of Social Psychology. Milestones are the ones BeHabit marks.

How to use it

  1. Pick the day you started the habit, or the day you plan to.

  2. See which day you’re on and how far you are from the median of 66 days.

  3. Check your timeline: the study’s fastest, median and slowest dates, with streak milestones in between.

Questions

In the best-known study (Lally et al., 2010), the median time for a new daily habit to feel automatic was 66 days, with individuals ranging from 18 to 254 days. Simpler habits tended to form faster.

The 21-day figure comes from a 1960 self-help book, not from research on habits. The evidence points to about two months on average, with a wide range.

No. In the study, missing a single opportunity didn’t materially affect habit formation. What matters is getting back to it.

Read more: How long does it really take to build a habit?

Do it every day, in one tap

BeHabit marks quiet milestones along the way, and suggests raising a habit a notch once it has held for three weeks.

Get it on Google PlayiPhone version coming soon.

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