Menstrual Cycle Calendar
Calculate your next period, ovulation, and fertile window dates based on your last period start date and cycle length.
This calculation produces estimated future period dates based on the last period start date and average cycle length. Ovulation date is roughly calculated by subtracting the default luteal phase days from the next period start date.
This tool should not be used for medical diagnosis, treatment, birth control, or pregnancy planning decisions. Physician evaluation should be taken as a basis in health-related matters.
Frequently Asked Questions
How is the menstrual cycle calculated?
The menstrual cycle is the time from the first day of one period to the first day of the next period. Although it lasts 28 days on average, 21-35 days is also considered normal.
What is the ovulation period?
Ovulation is the release of a mature egg from the ovary. It generally occurs about 14 days before the start of the next period. This calculation is for informational purposes.
What does fertile window mean?
The few days before ovulation and the day of ovulation are the days when the probability of getting pregnant is highest. These are estimated results and do not indicate a definitive medical outcome.
