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
Dec 13, 2015Dec 9, 2015 - Dec 19, 2015Sep 5, 2016
Jan 10, 2016Jan 6, 2016 - Jan 16, 2016Oct 3, 2016
Feb 7, 2016Feb 3, 2016 - Feb 13, 2016Oct 31, 2016
Mar 6, 2016Mar 2, 2016 - Mar 12, 2016Nov 28, 2016
Apr 3, 2016Mar 30, 2016 - Apr 9, 2016Dec 26, 2016
May 1, 2016Apr 27, 2016 - May 7, 2016Jan 23, 2017

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

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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.