How to know when do you ovulate?

Figuring out when do you ovulate is an inexact science for most women. The love making process is easy when you are expressing your affection for your partner, but when it comes to procreation, nailing the timing down necessary to conceive successfully can be a surprisingly difficult task.

While the average reproductive cycle lasts roughly 28 days, the variance in that number from one woman to another can makes it near impossible to come up with a one-size-fits-all answer for everyone.  

Due to simple differences in biology and diseases/disorders that can afflict women, it’s important to take a methodical approach to determining the length of your reproductive cycle.

What is the most important thing to learn how to know when you ovulate? The primary concept that one should learn about is the fertile window. It is defined as the day of and the days immediately preceding ovulation.

The chance of you getting pregnant if you have sex six or more days before the opening of your fertile window is miniscule; studies have also shown that woman that have sex five days before ovulation have a probability of conception of 10% or less (1).

When the day of ovulation occurs, the probability of a pregnancy declines quickly, as the egg only has a 12 to 24 hour period of viability once released from the ovaries.

Learning when do you ovulate every month is vital to planning your lovemaking, so that you can give yourself the best possible chance of conceiving.

The basics: what is ovulation?

In order to properly understand when do you ovulate, it is helpful to learn about the nuts and bolts behind ovulation itself.

In the run-up to this crucial portion of the reproductive cycle, your body will produce an increasing amount of FSH, or follicle stimulating hormone.

This triggers the development of up to a dozen follicles per cycle. One of these will become the dominant follicle, releasing an egg into the fallopian tubes. It is here where it may encounter the sperm of a male, triggering a pregnancy.

Prior to the emergence of the dominant follicle, it and the rest of the follicles release oestrogen into the bloodstream in ever-increasing amounts.

When they hit a specific level, this will then trigger the release of luteinizing hormone, also known as LH.

Within 24 hours of this release, ovulation will occur, marking the climax of a woman’s fertile window during her reproductive cycle.

With this background knowledge established, let’s explore several ways you can figure out when your fertile window opens each month via evidence based ovulation tracking:

1) The Calendar Method

It has been revealed through many studies that a woman is at her most fertile two to three days before ovulation occurs. Sexual intercourse that occurs at this time has the best chance of resulting in a pregnancy.

When do you ovulate? While this is far from being a rule of thumb, the average amount of time from when a woman’s period begins and the time of ovulation is roughly 14 days.

This way point serves as a good place for you to begin charting your reproductive cycles. By making a note of when you have your period for a few months, it is possible to hone in on the time when you are most likely to be fertile.

One thing that makes the calendar method difficult to follow is that not all reproductive cycles are exactly 28 days long. Reproductive cycles can be as short as 15 days, or as long as 45 days (2).

Additionally, external factors such as stress and/or the presence of metabolic disorders such as PCOS can result in delayed ovulation.

In some cases, ovulation may not even occur some months. When this occurs, it is helpful to address the underlying circumstances before attempting to nail down the time when your fertile window will be open via ovulation tracking.

Even under normal circumstances, the length of the reproductive cycle and the day of ovulation can vary by a few days from month to month, making the task of pinning down an exact schedule quite difficult.

However, sperm can live in a woman’s reproductive organs between three to six days after sexual intercourse (3). This gives you and your partner plenty of time to have properly-timed relations, provided that you are able to figure out the range of days when your fertile window is likely to be open.

If you suffer from irregular reproductive cycles (as those that have PCOS often do), it is important that you also pay attention to other signs that the ovulation portion of your reproductive cycle is imminent.

2) Track your basal body temperature

An increase in your basal body temperature is one of the primary signs ovulation is about to occur. Your basal body temperature is defined by how warm your oral or vaginal cavity is when you first wake up in the morning, before any activity occurs.

Recording it should be a central part of the journaling that you do over the few months when you are tracking your cycles.

There’s a special thermometer that you will need to use when tracking your basal body temperature; they are available at most pharmacies or through your doctor.

Each morning, be sure to take your temperature either orally or vaginally. Do not switch up venues during the course of your tracking, as temperatures in your oral and vaginal cavities can vary considerably. This difference in data may throw off your ovulation tracking completely, so stick to one area specifically.

An important thing to consider is that you will not generally feel the difference in your body when your basal body temperature rises. The difference between your normal basal body temperature and your ovulation temperature can be as little as 0.4 to 1 degree Fahrenheit (4). This makes it tough to answer the question, “when do you ovulate?”, without reading your temperature using a thermometer every single day.

What’s more, your basal body temperature will be at its lowest point in the entire cycle just before ovulation occurs, so it is important that you take this task seriously in order to obtain good data.

Be vigilant when taking your basal body temperature, as picking up on a pattern requires consistent effort on your part.

For best results, be sure to take your temperature as soon as you get up in the morning, and no later than three hours afterward, as hormones released and daily physical activity that takes place after you wake up can skew results.

Since basal body temperature rises after ovulation has occurred, it is essential that you do not use this method to pinpoint when exactly to have sexual intercourse, as the egg will have likely expired after this event has occurred.

However, using it to pinpoint the exact day of ovulation across several reproductive cycles can help you chart roughly when your fertile window is open during any given month.

3) Keep an eye on your cervical mucus

At the beginning of your reproductive cycle, there is very little to no cervical mucus that gets discharged from your vagina.

As the days progress however, some begins to come out, and it tends to be thick and cloudy in its consistency when it does.

Around ovulation time, oestrogen production increases dramatically, causing the discharge to become thin and slippery, much like raw egg whites.

It is theorized that cervical mucus becomes thin and slippery during ovulation so that the transport of sperm to an unfertilized egg can be easily facilitated.

It also serves to protect the sperm from the naturally acidic environment that exists in the vagina, and it also provides them with the nourishment that they need to survive until they manage to find a freshly-released egg in the fallopian tubes (5).

With this in mind, make a note of differences in your cervical mucus during the process of your ovulation tracking, as it is a great indicator of when your fertile window is beginning to open.

4) Pay attention to physical symptoms

In about 20% of women, a degree of physical discomfort will accompany the onset of ovulation. Typically manifesting itself as lower abdominal cramps, or as back pain on one side of your body, it is thought to be caused by the maturation and the release of an egg from one of the ovaries (6).

Known as mittelschmerz (German for middle pain) and lasting anywhere between a few minutes to a few days, it may not be a pleasant signal, but if you are if you are looking to know how when do you ovulate, this is one of the most salient signals that your body will give you.

Be sure to check your cervical mucus at the same time that these pain signals occur, as you will often find that your mucus is at its clearest and slipperiest at this point in your reproductive cycle.

That isn’t all the physical symptoms that are caused by this process though: there are other conditions that you should be looking for when you are trying to pin down your fertile window.

If you are approaching the fertile portion of your cycle, you will notice that your breasts will be more tender than usual, and you might find yourself acting more flirtatious than you usually are (7).  

When you are approaching ovulation, you may also notice that you are more receptive to having sexual relations than you are at any other time during your reproductive cycle.

Additionally, your partner may also pick up on these cues, as the pheromones released at this point tend to induce possessive and attentive feelings from them.  

Dating back to the times when competition for mates was intense, this forced him to focus on his partner, so that it was his sperm were the ones that fertilized the eggs of his desired partner, and not someone else’s.

5) Get familiar with your cervix

The cervix, which is the neck-like opening that exists between the vagina and the uterus, changes during the course of the reproductive cycle.

However, the differences are slight, making it important for you to get familiar with the differences in your cervix before and during ovulation.

While the cervix is often stiff and closed up prior to ovulation, it softens up and opens slightly just before its occurrence. Presumably, this is to allow sperm easy access to this part of the reproductive organs of a female (8).

It is vital that you get familiar with the differences in texture that your cervix goes through during the course of your reproductive cycle.

By documenting its changes on different days during your cycle, you can further pin down the days when your fertile window is open.

6) Pick up an ovulation prediction kit

One of the best ways to predict when you are most fertile is to make use of an ovulation prediction kit. By peeing on a stick, you will be able to know when you are at your most fertile during your cycle.

This test generally gives a positive result a few days before you actually ovulate, as it assesses the level of luteinizing hormone (LH) in your body.

The level of this hormone increases considerably when you are about to release an egg from your ovaries, making the use of an ovulation prediction kit an invaluable tool for ovulation tracking (9).

If urinating on an indicator stick isn’t what you are looking for in a fertility test, there are oral tests that work just as well.

These work by taking your saliva and measuring the amount of estrogen that can be found within a sample.

Put under a microscope, the estrogen in your saliva will produce a pattern that is roughly analogous to that of a fern if you are nearing the fertile portion of your reproductive cycle (10). While less exact than the stick test, it is often cheaper than using an ovulation prediction kit.

Another test that if you are looking to know when do you ovulate is a sweat test. By assessing the levels of chloride ions in sweat, those that use this test can get up to four days advance notice of when they will ovulate, as levels of this compound surge well before an egg is released from the ovaries (11).

In order for this to work however, it is important to establish a baseline for your normal ion levels before testing your sweat.

As such, the measuring device that assesses this benchmark should be worn for up to six hours during the early days of your reproductive cycle in order to know what your chloride ion levels are before ovulation occurs.

Figuring out your fertility window

Given the information above, working out when do you ovulate will become an easier task. Using the signs above, you can work out the days on when you’ll most likely be fertile. When you are tracking your menstrual cycle, the first day of your period is day one.  

Your fertile window should occur between day 12 and day 17, though this will vary from person to person.  

If you have irregular cycles (as is often the case with those who have PCOS),  the variance will be even larger, making it important to take detailed notes on the length and occurrences that happen during these cycles in order to pin down exactly when do you ovulate.   

Even if you have relatively consistent cycles,  the exact fertile window may wobble a few days in either direction due to a variety of reasons related to hormone levels and environmental circumstances such as stress.

If your cycles are relatively predictable, then there are web tools available that you can use to predict your fertile window.  

By searching for the term, “ovulation calculator”, inputting the first day of your period, and the average length of your cycle (this makes cataloging your cycle for a few months essential), you will be able to get a rough idea of when do you ovulate, making it easier for you to have a baby.  

Failing this, you can use the clues that your body gives you in the paragraphs above to more accurately pin down the time when your fertile window is usually open.  

If trying to connect all the dots is getting too complex for you, then simply having sex every two to three days after your period finishes may grant you better results than attempting to nail down the exact day when you will be the most fertile (12).  


Trying to figure out the question,  “when do you ovulate?”, is an inexact science for one woman, let alone those of an entire population. Due to circumstances that you may be dealing with, having a coordinated approach based on the cues that your body is giving you will yield better results than simply making love randomly and hoping for the best.  

While metabolic disorders such as PCOS can complicate matters considerably, pairing a treatment protocol for this disorder and having an organized approach to your attempts to conceive will give you the best chance of starting that family you’ve always dreamed of having.















Fertility Chef

Fertility Chef provides online PCOS diet & nutrition resources for women. Learn what a PCOS diet is & how it works.

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