Ovulation & Fertile Window Calculator
Enter the first day of your last period and your average cycle length to estimate your ovulation date, fertile window, and next period.
28 days
Enter the first day of your last period to calculate ovulation and fertile days.
※ Ovulation is estimated as "next period − 14 days", an average. Actual ovulation can vary by a few days with stress or health. For accuracy use an ovulation test or see a doctor. Do not use this as a contraception guide.