Choose a goal that matters
Create a focused project for the change you want to make, from moving more to spending less time scrolling.
A habit tracker for the long game
Build habits that last—one day at a time.
Turn one meaningful goal into small daily actions. Track your consistency, reflect on what worked, and give change a realistic runway.
For iPhone, iPad and Apple Watch · In-app purchases
A realistic runway
Your first 66 days
Day 42 of 6662%
Your pace can be different. Keep showing up.
Move for 20 minutes
Read 10 pages
Wind down before 11:30
Goal-based projects
Good and bad habit modes
English + 10 more app languages
The number, in context
66 days is a useful average—not a deadline.
In a University College London study, the average time for a repeated behaviour to feel automatic was 66 days. Individual results varied widely, from 18 to 254 days, and missing one opportunity did not materially derail the process.
So 66 Days gives you a clear horizon without pretending that change follows a stopwatch.
Simple enough to repeat
One goal. Small actions. An honest record.
66 Days keeps the system light so the habit—not the tracker—gets your attention.
Add the actions behind it
Break the goal into habits you can actually do today, then set reminders where a prompt will help.
Check in and learn
Mark what happened, add a note or photo, and use streaks and history as feedback—not judgement.
Built around real behaviour
The tools you need. Nothing to perform for.
A calm place to build good habits, reduce the ones that get in your way, and see the story your days are telling.
01
Projects with purpose
Group several daily actions under one meaningful goal instead of juggling a flat list.
02
Build the good. Reduce the bad.
Use a mode that matches the change: repeat a helpful action or notice and interrupt an unwanted one.
03
Streaks and history
See daily consistency, longest streaks and activity over time without turning progress into pressure.
04
Notes, photos and reminders
Capture context when it helps and set timely prompts for the actions that are easy to forget.
05
Close at hand
Check in from iPhone, iPad or Apple Watch, and glance at remaining habits from the home-screen widget.
06
Your pace, your language
Use the app in English and ten additional languages, with light and dark appearances.
Clear about your data
Personal habits deserve a plain-language policy.
The app stores habit information on your device and may sync it through Apple iCloud. Current production versions may use product analytics, while Epipherse handles support by email. This website has no advertising trackers or non-essential cookies.
- No separate 66 Days account is required
- Apple handles App Store purchases
- Data categories and service providers are listed in full
Good to know
A few honest answers before you begin.
01Will I definitely form a habit in exactly 66 days?
No. Sixty-six days was the average in one influential study, not a guarantee. The same study found wide variation between people and behaviours. Treat day 66 as a useful horizon, then keep the routine that works for you.
02What if I miss a day?
A missed check-in may affect an in-app streak, but it does not erase what you have learned. The research suggests one missed opportunity does not materially derail habit formation. Resume with the next useful action.
03Is 66 Days free?
The app is free to download and includes in-app purchases. Optional subscriptions and one-time purchases unlock additional features. Current local pricing and terms are always shown by the App Store before purchase.
04Which devices are supported?
66 Days is available for compatible iPhone, iPad and Apple Watch devices. Compatibility requirements can change, so the App Store listing is the source of truth for your device.
05Where is my data stored?
Habit records are stored on your device and may sync through iCloud on supported versions. Some usage analytics and support information are processed by service providers. The Privacy Policy explains the exact categories and purposes.
Start where you are
Give the next 66 days a direction.
Choose one meaningful goal, make the actions small, and let consistency do the quiet work.
Start your first 66 days