Does a new habit really take 21 days?
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How long does it really take to form a habit?
In one study, 96 volunteers each picked one small thing to eat, drink or do at the same moment every day for 12 weeks, and rated how automatic it felt.
On average it took 66 days to feel automatic. The fastest took 18 days, the slowest an estimated 254.
Missing one day didn't materially change it. If day 21 still feels hard, you're not behind.
Sources
Lally P et al. Eur J Soc Psychol 40:998-1009. doi:10.1002/ejsp.674
University of Surrey news, 21 Jan 2026 (Dr Pippa Lally)
What the study says
- “To investigate the process of habit formation in everyday life, 96 volunteers chose an eating, drinking or activity behaviour to carry out daily in the same context (for example 'after breakfast') for 12 weeks.”
- “The time it took participants to reach 95% of their asymptote of automaticity ranged from 18 to 254 days”
- “Missing one opportunity to perform the behaviour did not materially affect the habit formation process.”
- “The average time it took for the participants in my study to form a daily habit was 66 days.”
- “It was a groundbreaking finding that challenged the long-held view that it takes only 21 days to form a habit.”
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