Estimate ovulation day and fertile window.
Average cycle is 28 days. Range: 21-35 is common.
Estimated Ovulation Day
Fertile Window
6-day window (5 days before + ovulation day)
Next Period
Next 3 Cycles
Estimates based on the calendar method. Ovulation typically occurs 14 days before the next period.
Enter the first day of your last period and your cycle length to estimate your fertile window.
This ovulation calculator estimates your most fertile days based on your menstrual cycle. It helps identify the ovulation date and fertile window for family planning.
Ovulation typically occurs 14 days before your next period. The fertile window includes the 5 days before ovulation and the day of ovulation itself. Sperm can survive up to 5 days in the reproductive tract.
This calculator provides estimates based on average cycle lengths. Actual ovulation timing can vary due to stress, illness, and other factors. For accurate ovulation tracking, consider using ovulation predictor kits or tracking basal body temperature.