Habit streak calculator
Calculate how long a habit streak has lasted from a start date. See days, weeks, and months in your current streak. Free streak counter.
How the streak calculator works
Enter the day your streak began. The calculator counts every day from that date through today, counting the start date as day one, then subtracts the missed days you enter. The result is your streak in days, the full weeks in it, and the approximate months, using 30.44 days per month.
For example, a streak that started 21 days ago has 22 days counting today. Enter 2 missed days and the streak becomes 20 days.
Streak milestones
| Days | Full weeks | Approx. months |
|---|---|---|
| 7 | 1 | 0 |
| 21 | 3 | 0 |
| 30 | 4 | 0 |
| 66 | 9 | 2 |
| 100 | 14 | 3 |
| 365 | 52 | 11 |
Habit advice often quotes 21 or 66 days for a habit to feel automatic. The best-known study, by Phillippa Lally and colleagues in 2009, found a median of 66 days with a wide range (European Journal of Social Psychology). Treat those as rough markers: how long it takes depends on the person and the habit, so use the count to see your own consistency instead of racing a number.
Streaks and the missed-day question
This calculator lets you subtract missed days, because many streaks are forgiving. In Left, a Streak increases automatically unless you restart it, and Restart lets you choose when the new count begins, while keeping the history of your restarts. A Habit works differently: it tracks completions on a schedule such as every day or three times a week. The streaks vs habits guide explains which to use, and the habit tracker page covers the widgets.
Questions
Is the start day counted?
Yes. The start date is day one, so a streak that began today is 1 day.
What are missed days for?
They are subtracted from the total, for streaks where you allow a few misses. Leave it at 0 for an unbroken streak.
How are the months calculated?
The days are divided by 30.44, the average month length, and rounded down.
Can I track the streak on my iPhone?
Yes. Add a Streak in Left and show it in a widget. The free plan includes 2 streaks.
Start noticing what matters.
Download Left on your iPhone to see the time you have left, dates you are looking forward to, build the habits you want to keep, and become a better version of yourself.
Scan or search "Left" on the App Store.