Ovulation Calculator

The Ovulation Calculator estimates the ovulation date and the corresponding due date if the pregnancy is based on normal biological cycles. It is not recommended to avoid pregnancy based on ovulation calculation.

First Day of Your Last Period:
Average Length of Cycles:

Most Probably*Ovulation WindowEstimated Due Date if Pregnant
Mar 20, 2015Mar 16, 2015 - Mar 26, 2015Dec 12, 2015
Apr 17, 2015Apr 13, 2015 - Apr 23, 2015Jan 9, 2016
May 15, 2015May 11, 2015 - May 21, 2015Feb 6, 2016
Jun 12, 2015Jun 8, 2015 - Jun 18, 2015Mar 5, 2016
Jul 10, 2015Jul 6, 2015 - Jul 16, 2015Apr 2, 2016
Aug 7, 2015Aug 3, 2015 - Aug 13, 2015Apr 30, 2016

* This date is based on the average of 14 days before the next period was due.

Related:pregnancy calculator

Ovulation is the process by which a mature ovarian follicle ruptures and discharges one or a few eggs in a female's menstrual cycle. This process is controlled by the brain via the release of the luteinizing hormone (LH) and the follicle-stimulating hormone (FSH). If the egg is fertilized by sperm, it may implant from 6 to 12 days later, at which point pregnancy begins.

The average ovulation time is 14 days before the first day of your next period. However, the ovulation day may vary among women. Therefore, cycle length alone is not a reliable indicator of your ovulation day. Ovulation tests are more accurate, having a 99% accuracy rate, and they can be purchased without a prescription.

Normally, ovulation test kits measure the LH level in urine. A surge of the LH level, or a "positive" test result indicates the onset of ovulation and the fertilization windows, which occur during the following three days.