Calculate Your Ovulation & Fertile Window
Predict your most fertile days based on cycle length. Plan conception or track your cycle.
How Ovulation Timing Works
Ovulation typically occurs 14 days before your next period, not 14 days after your last one. For a 28-day cycle, that is day 14. For a 32-day cycle, day 18. The fertile window spans 5 days before ovulation through 1 day after — sperm can survive up to 5 days in the reproductive tract, while the egg lives only 12-24 hours after release.
Maximizing Conception Chances
The highest conception probability is from intercourse 1-2 days before ovulation, not on ovulation day itself. Having intercourse every 1-2 days during the fertile window gives the best chances. Ovulation predictor kits (OPKs) detect the LH surge 24-36 hours before ovulation for more precise timing. Basal body temperature tracking confirms ovulation after the fact.
A study in the New England Journal of Medicine found that the probability of conception from a single act of intercourse peaks at 33% on the day before ovulation and drops to near zero by 2 days after ovulation. Timing matters more than frequency.
