28-day cycle
Sample
Cycle length 28, LMP start
What you get
Fertile window estimate (not contraception).
Ovulation Calculator
Cycles vary; lh tests and BBT give more individual signal.
Ovulation Calculator
YearMonthDay
Approx. ovulation
Jun 15, 2025
Fertile window (rough)
Jun 10, 2025 – Jun 16, 2025
These tools provide general fitness estimates only and are not a substitute for professional medical advice.
How to Use This Tool
- Enter last period start date.
- Set typical cycle length (21–45 days).
- Review approximate ovulation and a rough fertile window.
Features
- Ovulation ≈ cycle length − 14 from LMP
- Fertile window span
- Educational use
Example
Frequently Asked Questions
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