28-day cycle
Sample
Cycle length 28, LMP start
What you get
Fertile window estimate (not contraception).
Ovulation Calculator
Estimate ovulation and a rough fertile window from last period start and typical cycle length (about cycle length minus 14 days for ovulation). Cycles shift with stress, travel, and hormones; LH tests and basal body temperature give more individual signal. Educational use only—not contraception advice.
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
How is ovulation day estimated?
From LMP and cycle length we approximate ovulation near cycle length − 14 days and show a rough fertile window. LH tests improve individual timing.
Is this medical advice?
No. This calculator is for general education and planning only. Always consult a qualified clinician for personal health decisions.
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