Ovulation Calendar – Fertility Calculator

Ovulation Calendar

Use our calculator to pinpoint your ovulation and determine your fertile days, the sweet spot in your menstrual cycle during which your chances of conceiving are the highest.

Ovulation and Fertile Days Calculator

The ovulation and fertile days calculator helps you get an approximate estimate of the fertile days during which conception is possible. Exactly how reliable the calculation of fertile days will be depends on the accuracy of the data you enter, as well as the regularity of your menstrual cycles.

 Ovulation Calculator

Try our free ovulation calculator to find your most fertile days and the best time to conceive.

Select the first day of your last period:

How long is your average cycle?

What Is Ovulation?

Ovulation is a part of a normal menstrual cycle, the precise term denoting the release of a mature egg from the ovary and down the fallopian tube, where fertilization by sperm may occur. The menstrual cycle is calculated from the first day of one menstruation to the first day of the next one. Although the menstrual cycle differs from person to person, for most women it lasts between 28 and 32 days. Every menstrual cycle lasting between 24-35 days is considered normal.
Ovulation corresponds to a time period of 12 to 24 hours when the egg cell is ready for fertilization. During this period, sexual desire increases as the testosterone levels rise by 30%.

There is a widespread misconception that a woman can only get pregnant if she has intercourse sometime during the 24 hours of ovulation. Although this is a period of optimal conditions for fertilization, it is very much possible for pregnancy to occur even when you are intimate outside of that frame because sperm can survive in a woman’s body for up to 5 days. Therefore, if you are trying to conceive it is important to have sexual intercourse before and during ovulation.


When Does Ovulation Occur?

Ovulation depends on the length of your cycle. For example, during the average cycle (28 days), ovulation occurs somewhere between 13-15 days (counting from the first day of the cycle) before the first day of the following menstruation. The period may vary between 10-16 days.

Fertile Days

The method of determining fertile days is very simple. To use this method, you need to know the length of your cycle (28 days on average). During the cycle there are two phases.

  • The first phase (which varies in duration for women with irregular cycles) lasts from the beginning of menstrual bleeding to ovulation.
  • The second phase, encompassing a period from ovulation to menstruation, is invariable and lasts for 14 days (13-16 days).

By subtracting 14 from the length of the average cycle (28 days), we determine the day when ovulation occurs (egg release). In order to get a period of fertile days, we subtract 14 from the length of the menstrual cycle and reduce the number by another 3 days (since sperm can survive for up to 78 hours following intercourse).

Example: A woman with an average menstrual cycle of 28 days has fertile days between days 11 and 17 of the menstrual cycle.
It is important to emphasize that this method is unreliable for women whose length of the menstrual cycle varies. Still, the fertile days method can serve as a good auxiliary method for timing sexual intercourse if you are trying to conceive or if you want to protect yourself from unwanted pregnancy.

Ovulation Symptoms

Vaginal Discharge (Cervical Mucus)

By observing changes in vaginal discharge, we can roughly determine the day of ovulation. There are significant changes in the amount, color and stretchiness of the cervical fluid.

  • During the first phase, immediately after menstruation (days 5-9), the vagina and the vulva are dry.
  • In the second phase (days 9-10), the vagina begins to moisten, and the mucus is yellowish, sticky and inelastic.
  • In the third phase, during ovulation, the mucus becomes abundant, translucent and very stretchy.

After ovulation, the mucus becomes sticky once more.

Abdominal Pain

1/5 women can feel the changes occurring in ovaries during ovulation. The sensations vary from a slight twinge or a slight burning sensation in the ovaries to severe pain in the abdomen, not unlike menstrual pain. Usually the pain is localized only on one side of the abdomen, and can be accompanied by back pain and sensitivity in some other parts of the body.

Cramping may also occur as a result of the egg making its way through the fallopian tube down to the uterus.

Abdominal Pain


Ovulation can cause slight bloating, very similar to the one experienced during menstruation. Hormonal changes are the most common cause of this bloating.


Women rarely notice light red spots during mid-ovulation and even if they do, they take it for residual menstrual blood. However, these stains occur when the egg bursts out of the ovarian follicle during ovulation, thus indicating fertility.

Measuring Body Temperature

During ovulation, body temperature increases by 0.3-1 ° C. Measuring body temperature throughout the menstrual cycle helps in predicting ovulation. Body temperature should be taken every morning after getting out of bed. During ovulation, the temperature rises drastically, by up to half a degree.

Ovulation and Pregnancy

Ovulation and conception are closely related. A woman’s fertile period is limited to ovulation day, a couple of days preceding (since residual sperm can fertilize the egg) and three days following ovulation. Sperm cells can survive 3-5 days after ejaculation, and the egg cell only 24 hours after ovulation. In a normally fertile couple, the chances of conception during ovulation in each cycle equal 25%, which points to the fact that 75-85% of women get pregnant in the first year of trying.

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