A new habit took 66 days, on average, to become automatic.
Some people got there in 18 days. For others it would take an estimated 254.
Phillippa Lally and colleagues at University College London asked volunteers to repeat one new behaviour every day and to rate how automatic it felt. On average, automaticity levelled off after 66 days.
The spread was wide, and missing a single day did not reset the curve. First Flight uses 66 days as the line where a Move becomes Owned, and turbulence never resets the count.
96 volunteers, 82 completed the 84-day study; the 254-day figure is an extrapolation. European Journal of Social Psychology, 2010. The curve shown is an illustrative model of the average participant.