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
Jan 1, 2015Dec 28, 2014 - Jan 7, 2015Sep 25, 2015
Jan 29, 2015Jan 25, 2015 - Feb 4, 2015Oct 23, 2015
Feb 26, 2015Feb 22, 2015 - Mar 4, 2015Nov 20, 2015
Mar 26, 2015Mar 22, 2015 - Apr 1, 2015Dec 18, 2015
Apr 23, 2015Apr 19, 2015 - Apr 29, 2015Jan 15, 2016
May 21, 2015May 17, 2015 - May 27, 2015Feb 12, 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.