Ovulation Calculator

The Ovulation Calculator estimates most probable ovulation date as well as other related. The estimations are calculated using information such as the first day of a person's last period and the average length of their menstrual cycles in conjunction with what is known regarding typical biological cycles. This calculator should not be used as a form of birth control.

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

Most Probable Ovulation DateOvulation WindowFertile WindowNext PeriodPregnancy TestDue Date if Pregnant
Mar 7, 2019Mar 3 - Mar 11Mar 3 - Mar 8Mar 21, 2019Mar 16, 2019Nov 29, 2019
Apr 4, 2019Mar 31 - Apr 8Mar 31 - Apr 5Apr 18, 2019Apr 13, 2019Dec 27, 2019
May 2, 2019Apr 28 - May 6Apr 28 - May 3May 16, 2019May 11, 2019Jan 24, 2020
May 30, 2019May 26 - Jun 3May 26 - May 31Jun 13, 2019Jun 8, 2019Feb 21, 2020
Jun 27, 2019Jun 23 - Jul 1Jun 23 - Jun 28Jul 11, 2019Jul 6, 2019Mar 20, 2020
Jul 25, 2019Jul 21 - Jul 29Jul 21 - Jul 26Aug 8, 2019Aug 3, 2019Apr 17, 2020


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Ovulation and Conception

Ovulation in humans is the process by which ovarian follicle(s) rupture and release a mature egg from the ovaries. On average, ovulation occurs within the 4 days before or after the midpoint of a woman's menstrual cycle (14 days before the start of a woman's next menstrual period). Menstrual cycles vary between women however, and a person without a 28-day menstrual cycle may need to track their menstrual cycle to more accurately determine when ovulation might occur.1 It is also possible to use an over-the-counter ovulation test that tests for a surge in some specific hormones that precede ovulation by 24-48 hours. While these tests are 99% accurate in detecting the specific hormones, they cannot guarantee when exactly ovulation will occur within the two-day period.2

Day 10-18 of the menstrual cycle (on average) is the most fertile phase of the menstrual cycle. This is important when trying to conceive because fertilization of the egg can only occur for 12-24 hours after release during part of the luteal phase, when a mature egg travels through the fallopian tubes towards the uterus. Since sperm can survive inside a woman's body for up to five days, regular sex five days before and on the day of ovulation can improve the likelihood of conception.1 If fertilized, the egg will implant in the uterus 6-12 days later. Otherwise, menstruation occurs, and blood and mucosal tissue from the inner lining of the uterus is expelled.


  1. Mayo Clinic. 2016. "What ovulation signs can I look out for if I'm hoping to conceive?" www.mayoclinic.org/healthy-lifestyle/getting-pregnant/expert-answers/ovulation-signs/faq-20058000.
  2. American Pregnancy Association. 2016. "Ovulation Kits & Fertility Monitors." americanpregnancy.org/getting-pregnant/ovulation-kits/