Advanced Fertility Calculator
Ovulation Calculator
Estimate your ovulation day, fertile window and next expected period using the first day of your last period and your average cycle length.
Fertile Window Starts
Estimated Ovulation
Fertile Window Ends
Next Expected Period
How this ovulation calculator works
This calculator estimates ovulation by assuming that ovulation usually happens around 14 days before the next period.
The fertile window is shown as the days leading up to ovulation plus the ovulation day itself, when pregnancy is most likely.
This tool provides an estimate only. Real ovulation timing can vary from cycle to cycle.