The DayCalc.io Fertility Tracker helps you identify your most fertile days each cycle. Enter the first day of your last period and your average cycle length, and we'll calculate your estimated ovulation day, fertile window, and optimal days for conception.
Ovulation typically occurs about 14 days before the start of your next period. The fertile window is the 6-day stretch ending on ovulation day — sperm can survive in the reproductive tract for up to 5 days, while an egg is viable for about 24 hours after release.