Fertility Window Calculator

The fertility window is the 6-day period when conception is possible — 5 days before ovulation and ovulation day itself. Ovulation typically occurs 14 days before the next period.

1. 1Ovulation ≈ Cycle length − 14 days from LMP
2. 2Fertile window = Ovulation − 5 days to Ovulation day
3. 3Sperm survive 3–5 days; egg survives ~12–24 hours
4. 4OPK tests and basal body temperature confirm ovulation