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Period Calculator
Predict your next menstrual cycles, ovulation date, fertile window, and PMS phase — all in seconds.
28d
Cycle Length
5d
Period Days
Day 14
Ovulation Day
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Your Upcoming Cycles
Period
Ovulation
Fertile Window
PMS Phase
| # | Period Start | Period End | Ovulation Date | Fertile Window | Next PMS Starts |
|---|
This calculator provides estimates based on average cycle data. Results are for informational purposes only and are not a substitute for professional medical advice. Cycle lengths can vary due to stress, health conditions, medications, and other factors.
What is a Menstrual Cycle?
- Counted from Day 1 of your period to Day 1 of the next
- Average length is 21–35 days
- Hormones control the four cycle phases
- Irregular cycles are very common
- Tracking helps spot patterns over time
Understanding Ovulation
- Typically occurs ~14 days before your next period
- Fertile window spans 5–6 days around ovulation
- Sperm can survive up to 5 days inside the body
- Ovulation can shift due to stress or illness
- Basal body temperature rises slightly at ovulation
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