The Ovulation Calculators

When are you most fertile?

The ovary is the reproductive organ inside a woman that has the ability to make eggs. Typically, one egg is released from one of the two ovaries every month. This process is called ovulation. Once released, the egg is picked up by the fallopian tube and begins its journey towards the womb. For spontaneous conception to occur, the man must ejaculate his semen, the fluid containing the sperm, into the woman’s vagina near the time of ovulation. The man’s sperm must be capable of swimming through the vagina and the neck of the womb into the womb, and up into the fallopian tube, where it must attach to and penetrate the egg in order to fertilise it. The fertilised egg remains in the fallopian tube for a few days and then continues traveling to the womb and implants in the lining of the womb, where it grows and matures.

Ovulation is triggered by a surge of the luteinising hormone (LH) in the woman’s blood, and occurs approximately 36 hours after the start of the LH surge. If the egg is fertilised and implants in the womb lining, a pregnancy is established. If a pregnancy is not established, the womb lining that develops in preparation for pregnancy is shed and this results in the menstrual flow.

Taking charge of your fertility

If you have regular cycles you can assume that you are ovulating. The egg survives 24 hrs and the sperm survives up to 72 hrs. Hence, the recommendation is to have intercourse 3-4 times a week to optimise your chances of getting pregnant. 

Fertility tracker

  • The use of the period calendar (also known as the fertility calendar, fertility calculator or conception calculator) predicts the timing of ovulation and is popular amongst those who are trying to get pregnant.
  • The fertility cervical mucus test – How to check cervical mucus? When the consistency of the cervical mucus is like raw egg white it allows the sperm to swim easily into the cervix. It can stretch an inch or two between the fingers without breaking in the middle. These are your most fertile days. 

Ovulation Tester or Fertility Test

There are several ways to detect LH surge such as the urine test kits, blood tests and the basal body temperature (BBT) chart.

  • Urine Test Kits: Ovulation prediction test kits can be purchased from a pharmacy or on the internet. Clear blue ovulation test sticks are very well popular. These kits use test strips that reflect changes in the level of LH in the urine based on the colour change on the strip. For women with 28-day cycles, ovulation usually occurs on days 13 to 15. Urine testing should start 18 days prior to your shortest menstrual cycle length. Once ovulation is documented, it is no longer necessary to continue testing during that cycle. Occasionally, ovulation may not occur in a particular cycle. If ovulation is not detected in two or more consecutive cycles, an ovulatory problem may be present. You should discuss this with a fertility consultant.
  • Blood Tests to Measure Hormone Levels: As the egg sac (follicle) grows the LH level and the Estrogen level rise. Serial measurements of these hormones can be done to detect the development of the follicle. Elevated progesterone levels in the blood confirm ovulation. A blood test to measure progesterone can be performed about one week before the anticipated onset of the next menstrual period.
  • Basal Body Temperature (BBT) Chart: Prior to ovulation the woman’s body temperature is relatively low. When progesterone production begins at ovulation, it produces a temperature rise with a minimum increase of 0.5 degrees Fahrenheit. An increased body temperature for several days indicates ovulation has occurred. BBT charts which are plotted by the use of the fertility thermometer confirm that ovulation has occurred after the event.

Follicular tracking or ovulation monitoring by transvaginal ultrasound scans

Follicular growth can be measured with the help of serial ultrasound scans. Prior to ovulation, the follicle is thin-walled and filled with fluid. As the egg inside the follicle develops, the follicle increases in size. Ovulation generally occurs when the follicle measures about 1.5 to 2.5 centimetres. Post ovulation the follicular sac disappears for a short duration. Subsequently, it fills up and forms what is known as the corpus luteum.

Fertility Apps

There are many applications available that can predict your fertile days. is a very popular site if you would like to download an app to track your cycle.


These simple measures will provide reassurance to you when you embark on your fertility journey. If you are worried that you are not ovulating speak to our fertility consultant as there are treatments available to correct the problem and improve your chances of conceiving spontaneously.


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