Period Calculator
Use this calculator to estimate the future period days or the most probable ovulation days.
Result:
Next 3 Months Calendar
Important dates for the next 6 cycles:
| Period | Most Probable Ovulation Days |
|---|
Menstrual Cycle Overview
The menstrual cycle is a natural monthly process where a woman’s body prepares for potential pregnancy. Beginning at puberty (typically age 12-15) and ending at menopause (average age 52), each cycle starts on the first day of menstruation and lasts until the next period begins. Hormonal fluctuations regulate this process, with cycle lengths varying between individuals—though 28 days is average. A cycle is considered regular if variations between shortest/longest cycles are under 8 days.
Key Phases
- Menstruation (Days 1-7 avg): The uterus sheds its lining if no pregnancy occurs, resulting in 2-7 days of bleeding.
- Follicular Phase: The uterus rebuilds its lining while an egg matures.
- Ovulation (~Day 14 in 28-day cycle): An egg is released, with peak fertility occurring 5 days before through 1-2 days after ovulation.
- Luteal Phase: The body either supports a fertilized egg or prepares to restart the cycle.
Period Calculator Function
This tool predicts:
- Period Days: Expected menstruation dates
- Ovulation Window: Most fertile days (5-day span around ovulation)
Note: Cycles pause during pregnancy and breastfeeding, and end permanently at menopause (no periods for 12 consecutive months).