A look at your next period starts.
The calculator continues your average cycle length. It predicts nothing about your body; it shows which days the arithmetic lands on if your cycle length stays the same.
Your cycle takes shape here
Enter your last period start in the form. Your calculated date ranges will appear here.
This ring is only an example of a 28-day cycle.
Your inputs stay when you switch views. Opening a new page starts with empty inputs. Open this view on its own page
An orientation based on your inputs
The calculator repeats your cycle length. If your last period started further back, it shows the calculated cycle that contains today. It does not detect actual bleeding or phases. The results are not suitable for contraception, diagnosis or identifying ovulation.
Good to know
How are the six dates calculated?
The calculator repeatedly adds your cycle length to the period start you entered. It shows the next six calculated starts after the cycle that contains today.
Does the calendar show how long bleeding lasts?
No. Each date is only a possible start according to your calculation. Cycle length does not tell us how long bleeding lasts.
What if my cycles are irregular?
A fixed average length cannot reflect variation. The six dates are therefore not reliable predictions. They only show how your entered length repeats.
Does the calculation handle different months and leap years?
Yes. It counts calendar days across month and year boundaries. For example, a 28-day cycle starting on 15 February 2024 leads to 14 March 2024.
Follow your phases day by day in the BodySeasons app
In the app you record how you actually feel and recognise your own patterns across weeks and cycles. No points, no streaks, no grading.
Explore BodySeasons