Track your menstrual cycle, predict ovulation day, fertile window, and next period date. 100% private — all calculations happen in your browser.
Ovulation typically occurs about 14 days before your next period starts. This calculator estimates your fertile window — the days when conception is most likely — based on your last period date and average cycle length. The fertile window usually spans 5-6 days: the 4 days before ovulation, the day of ovulation, and the day after. Remember that every body is different, and this tool provides estimates for planning purposes.