Fertility Window Calculator
Calculate Fertility Window
Find your most fertile days this cycle
Formula
Ovulation Day = Cycle Length - 14 | Fertile Window = Ovulation Day - 5 to Ovulation Day + 1 | Peak Fertility = Ovulation Day - 2 to Ovulation Day | Implantation = Ovulation + 6 to 12 days.
Frequently Asked Questions
What is the fertility window?
The fertility window is a roughly 6-day period each cycle when pregnancy is possible: the 5 days before ovulation and the day of ovulation itself. This is because sperm can survive up to 5 days, while the egg lives only 12-24 hours. Peak fertility is the 2-3 days before and including ovulation.
How can I confirm when I'm ovulating?
Methods to detect ovulation include: ovulation predictor kits (OPKs) that detect LH surge 24-36 hours before ovulation, basal body temperature tracking (temp rises 0.4-0.8 degrees F after ovulation), cervical mucus changes (becomes clear and stretchy), and fertility monitors.
What are the chances of getting pregnant during the fertile window?
When timing intercourse during the fertile window, the chances of conception per cycle are: 1 day before ovulation ~30%, 2 days before ~27%, ovulation day ~10-12%, 3 days before ~7-8%. Cumulative chance with well-timed intercourse throughout the window is about 25-30% per cycle for healthy couples under 35.