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
Sep 3, 2017Aug 30, 2017 - Sep 9, 2017May 28, 2018
Oct 1, 2017Sep 27, 2017 - Oct 7, 2017Jun 25, 2018
Oct 29, 2017Oct 25, 2017 - Nov 4, 2017Jul 23, 2018
Nov 26, 2017Nov 22, 2017 - Dec 2, 2017Aug 20, 2018
Dec 24, 2017Dec 20, 2017 - Dec 30, 2017Sep 17, 2018
Jan 21, 2018Jan 17, 2018 - Jan 27, 2018Oct 15, 2018

* 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.