Fertility Window Calculator
Calculate your most fertile days and complete fertility window for conception planning.
The Fertility Window Calculator identifies your most fertile days within each menstrual cycle. It provides both the broader fertile window and the peak fertility days for optimal conception timing.
Enter the day your last period started and your average cycle length. The calculator estimates the 7-day fertile window (5 days before ovulation through 1 day after) and highlights the 3 most fertile days (2 days before through ovulation day).
The peak fertile days are when the probability of conception is highest. Studies show that intercourse on the day before or the day of ovulation has the highest chance of resulting in pregnancy.
Frequently Asked Questions
What are the most fertile days?
The 2-3 days immediately before and including the day of ovulation have the highest conception probability, approximately 25-30% per cycle.
Can I get pregnant outside the fertile window?
It is very unlikely but not impossible. Sperm can survive up to 5 days, and ovulation timing can vary. The fertile window captures the most likely days.
How can I increase fertility?
Have regular intercourse during the fertile window, maintain a healthy weight, reduce stress, avoid smoking and excessive alcohol, and take prenatal vitamins with folic acid.