How it Works
1. Log 'Last Period'.
2. Set 'Cycle Length'.
3. Calculate peak fertility window.
What is Fertility Window Predictor?
Determines the likely days of high fertility by analyzing menstrual cycle length and the standard 14-day luteal phase.
Step-by-Step Guide
- Log Start – First day of period.
- Define Cycle – Days between periods.
- Project – Ovulation date.
Example
Input: 28 Day Cycle
Result: Day 14 Peak
FAQ
How long does sperm survive?
Up to 5 days in fertile cervical mucus.
How long does the egg last?
Only 12-24 hours after release.
What if cycles vary?
Use your average cycle length or track for 3 months.
Luteal phase?
Usually constant at 14 days, even if cycle length varies.
Signs of ovulation?
Temp rise, Mittelschmerz, EWCM.
⚕️ Safety First: This calculator provides general health estimates. It does not replace a clinical assessment by a doctor.
Conclusion
The 'fertile window' includes the 5 days before ovulation and the day of ovulation itself. Tracking basal body temperature can improve accuracy beyond this mathematical model.