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Ovulation Calculator

Find your most fertile days by calculating ovulation date and fertile window from your last period and cycle length.

Your Cycle
First day of last period
Cycle length
days
Luteal phase
days
Show next
cycles
Results
Next Ovulation
EventDate
Fertility Calendar

Understanding Your Cycle

Ovulation typically occurs 14 days before the next expected period (not 14 days after the last period). The fertile window is approximately 5 days before ovulation plus the day of ovulation (6 days total), as sperm can survive 3–5 days in the reproductive tract.