Enter the first day of your last period to see your ovulation estimate.
How to use this calculator
Enter the date of the first day of your last period and your typical cycle length in days (most people are between 21 and 35 days). The calculator estimates your next ovulation date, the surrounding fertile window, and the expected start of your next period.
Understanding your result
Ovulation is estimated to occur about 14 days before the next period. The fertile window shown spans the 5 days before ovulation through the day after — this is when conception is statistically most likely. These are statistical averages; your cycle may vary from month to month.
Disclaimer
Menstrual cycles and ovulation timing vary significantly between individuals and from month to month. These predictions are statistical estimates and should not be used as a sole method of contraception or fertility planning. This is not medical advice. If you are trying to conceive, struggling to conceive, or have concerns about your cycle, consult a gynaecologist or healthcare provider.
Track your cycle in OptiAI
Log your period, track your cycle history, and see your ovulation and fertile window predictions over time in OptiAI.