Ovulation Calculator
Ovulation is when an ovary releases an egg, and it usually happens about 14 days before your next period. This calculator estimates your most fertile days, your likely ovulation date and your upcoming periods from the first day of your last period and your average cycle length.
Ovulation Calculator
How ovulation is estimated
The calculator counts forward from the first day of your last period by your average cycle length to find your next period, then counts back about 14 days to estimate ovulation. The fertile window is the five days before ovulation plus ovulation day itself.
Good to know
Ovulation timing can vary even in regular cycles, so treat these dates as an estimate. For trying to conceive, the days just before and on ovulation are the most fertile.
Frequently asked questions
When do I ovulate?
Ovulation usually occurs about 14 days before your next period starts. In a 28-day cycle that is around day 14, counting from the first day of your last period.
What is the fertile window?
The fertile window is the roughly six days ending on ovulation day, because sperm can survive for several days and the egg lives for about 24 hours.
How accurate is an ovulation calculator?
It gives a good estimate for regular cycles, but ovulation can shift. Tracking basal temperature or using ovulation tests gives a more precise result.
Can I get pregnant outside the fertile window?
It is much less likely, but possible, since cycle length and ovulation timing can vary from month to month.
What if my cycle is irregular?
With irregular cycles the estimate is less precise. Enter your average cycle length, and consider ovulation tests for a clearer picture.