When Do I Ovulate?

When do I Ovulate - Ovulation Explained

You never imagined that this one innocent question come to dominate your life for a couple months did you?

You even find so many ways to ask same question:

When is the best time to have sex to conceive?

  • When is my fertile window?
  • How many days after my period do I ovulate?
  • How do I know when I’m ovulating?
  • How long does ovulation last for?
  • The list goes on…

You start to feel like your whole life starts to revolve around this question. And for good reason…

Every month you only have a 33% chance of conceiving if you have sex on the day you ovulate. You could be trying to get pregnant for 3 months but just have been unlucky each time. There probably isn’t anything wrong with you –you were just unlucky!

This is why timing sex to when you are ovulating is so important.

 I Know When I Ovulate!…At Least I Think I Do.

At the beginning the answer to the question “When do I ovulate?” seemed so simple. Didn’t it?

If your fertility tracking app is telling you that you ovulate on day 14 of your cycle, then you say to yourself “I ovulate on day 14”. And that was that. But here’s the thing…

Unfortunately for a lot of women it is never as simple as this. Just because your app says you are ovulating on day 14 of your cycle doesn’t mean that you actually are ovulating on day 14 of your cycle!


The vast majority of fertility and period tracking apps simply subtract 14 days from the first day of your period and say that is the day you are going to ovulate on. This works for some women, but the same way that everyone looks different, everyone’s bodies works slightly differently as well.

Some women might a slightly shorter follicular phase (the days between day 1 of your period and the day you ovulate) and ovulate on day 10. While other women might have a slightly longer follicular phase and ovulate on day 17 or 18 of their cycles. 1 All things a fertility app doesn’t know!

This can be further complicated if you have an irregular cycle or if you have polycystic ovary syndrome (PCOS) for example. Both of which could cause the day you ovulate to change every month.

This brings me to my very close friend Jess…

Jess recently got married to her lovely husband Paul. (Their wedding was amazing by the way. She looked so beautiful in her wedding dress!)

She was so excited about starting her family. She had it all planned out…

Start taking some prenatal vitamins, eat a little healthier and start trying to get the timing right with Paul. And after a few weeks of trying it would be bada bing – bada boom – a trip to the mall for baby clothes!

However, after a few months and still no baby, Jess was starting to get worried. Was she doing something wrong? Or, was there something wrong with her? Jess just wanted to answers.

So she compiled a big list of questions and made an appointment with her doctor. She spoke to her doctor but she was really surprised by what she told her!

Jess was perfectly healthy. Her doctor couldn’t find anything wrong with her that could prevent her conceiving! What shocked her was how little she knew about fertility in general but more importantly about her own cycle.

Jess was told that instead of ovulating on day 14 as her fertility tracking app had told her she was ovulating, she was actually ovulating on day 18 of her cycle.

So for the last 4 months she had been trying to conceive by having sex on days 11, 13 & 14 of her cycle only to find out that her actual fertile window was days 15 to 18.  Although this was a shock at first, after thinking about it for a while she began to think of this realisation as empowering…

Whereas before she felt powerless and anxious about the thought that there might be something wrong with her. Jess now knew exactly what she was doing wrong and her doctor had given her a step by step plan to help her get her timing spot on every cycle.

The first thing he recommended for Jess to do was to learn some of the basics around ovulation. Starting with the most important question…

What is Ovulation?

Ovulation occurs when a mature egg is released from the ovary and begins to move towards the fallopian tube, in preparation to be fertilized. 2

The egg that you release during ovulation only has a lifespan of 24 hours.  So technically you can only get pregnant within these 24 hours of each monthly cycle.

I know what you’re thinking…

24 hours that is way too short, I thought  you could get pregnant for 3 to 6 days every cycle?

The Fertile Window

You are 100% right! But there is a difference between your fertile window and your ovulation.

As described above ovulation is when your ovaries release an egg into your fallopian tube so it can travel to your uterus. This egg can only survive in your fallopian tube for 24 hours unless it is fertilised with sperm. So if your egg isn’t fertilized within 24 hours of ovulation then it will degrade meaning you can’t conceive in that cycle.

So what’s the fertile window?

The fertile window is the 3 – 6 days before you ovulate and the day of ovulation. Sperm can survive in your vaginal/uterus for up to 5 days after sex. Allowing you to have a longer fertile window then the 24 hour lifespan of the egg you release during ovulating. The length of your fertile window can be shorter or longer based on the quality of the sperm or how hospitable is your cervical fluid. 3

However, as with anything organic the older the sperm is the more it degrades. This is why you want to ensure you are getting the timing right and having sex as close as possible to when you ovulate. It gives your partners sperm the best chance possible to fertilize your egg. This leads us to the most important question…

When Am I Most Fertile?

If you are trying to conceive you can be nearly certain this is the only question that you are concerned with. The great thing is the answer is pretty straightforward.

You are most fertile during the 2 days leading up to ovulation and the day of ovulation. If you have sex on any of these 3 days then you have a 27-33% chance of becoming pregnant! 4

chances of conceiving during ovulation

As you can see from the chart above, your probability of pregnancy increases from 0% of conceiving 6 days before ovulation to a 33% chance probability of conceiving, if you have sex on the day of ovulation. But if you get your timing wrong by only a day and have sex at the end of the ‘fertile window’, the probability of pregnancy declines rapidly and by 12-24 hours after ovulation and you are no longer able to get pregnant during that cycle.

Your most fertile days depend heavily on the length of your cycle. Ovulation happens approximately two weeks before the next expected period.

  • For example, if your average menstrual cycle is 28 days, you typically ovulate around the 14th day and the most fertile days include days 12, 13, and 14. 5
  • For a longer cycle, that may last 35 days between periods, ovulation would typically occur on day 21 and the most fertile days would include days 19, 20, and 21.
  • If your cycle is shorter, and you have 21 days between periods, ovulation could take place on day 7 and the most fertile days would include days 5, 6, and 7.

The general rule of thumb is that you ovulate 14 days before your next expected period. So determine how long your cycle is and then take 14 from it. However, this isn’t true for everyone. Some women might have a longer or shorter follicular phase which could mean that you ovulate either a couple days before or a couple days later. 6 The only way to find this out is to use some of the tracking techniques listed later in this article.

In Jess’s case, she know knew that she had a 32 day cycle so she knew she ovulated on day 18 so she could work out that her fertile window was day 13 to 18 but her most fertile days were the 3 days from day 15 to 18. So for Jess having sex six or more days before ovulation, meant her chance of getting pregnant was very low. While having sex five days before ovulation increased her probability of getting pregnant by 10% and so on till the day of ovulation.

Now you can see how incredibly important it is for you to get your timing right. As if you are off by even a couple of hours you could miss the window for another month.

Knowing this might make feel even more under pressure, but before you start freaking out you should stop reading right now and take a deep breath. As next we’re going to talk about the best piece of advice Jess’s doctor gave her which allowed her to pinpoint her day of ovulation every time…

Track Your Cycle!

Tracking your cycle is the most important thing to help you understand when you are most fertile. As see have already seen, you are your most fertile during the 2 days leading up to ovulation and the day of ovulation. So it is vital that you track your cycle so that you know when these days are.

In uncovering the length of your average menstrual cycle you can begin to track ovulation.  Day one of your cycle occurs on the first day of the menstrual period and the last being the day before the next period begins.

Through understanding her cycle, Jess could identify the exact three days leading up to and including ovulation in which she would be the most fertile in her cycle, so that she had the best chance of getting pregnant. These days were her “fertile window”, where herself and Paul knew when to get down to business. No more guessing!

How do you track your cycle?

What Jess didn’t realise before starting to track her cycle was that her body give us signals all the time. It was just a matter of knowing which signs to listen to.

  • Cervical Fluid:One of the strongest indicators of ovulation and what point you are in your cycle is how your cervical fluid changes throughout your cycle. 7 As your hormones fluctuate during your cycle they change the texture, color and amount of cervical fluid that is present in your vagina. If you a good understanding of how these changes relate to your cycle you can pin point where you are in your cycle at any time.  Typically your most fertile days is accompanied by clear watery cervical fluid that will be stretchy and will resemble egg whites. During this time your production of cervical fluid is at its peak. . When your cervical fluid starts to dry up it is a signal from your body indicating that ovulation is no longer taking place.
  • Basal Body Temperature: Charting your basal body temperature is another method of determining ovulation, which not only allows you to identify when you ovulate but also any other issues that might make it harder for you to ovulate. 8 In the second half of your cycle after you ovulate, progesterone is released to prepare the uterus for fertilisation. As a result, your body temperature is typically half a degree higher in the second half of your cycle compared to the first half. Temperature is a retrospective indicator of ovulation when the temperature has gone up it is indicative that ovulation has already occurred.

Conceiving your little baby boy or girl can be both a very rewarding and memorable experience but also a anxious one if it is taking a bit longer than you initially expected. The important thing to remember is that you’re not alone. Because of the nature of trying to conceive most couples never disclose the fact that they had trouble conceiving, most of the time it appears it was a simple and effortless process. But this rarely is the case, especially if you are a bit older.

Don’t lose hope though. You are still in the driver’s seat.

If you follow the guidelines we have outlined here and start tracking your cycle then you can take charge of your conception journey.

The Great News!

The nicest part – we are so thrilled to announce our lovely friend Jess was successful in her story! Her and her partner Paul had a beautiful baby boy – Noah. Jess’s advice – get to know more about your pregnancy process. She hopes her story will help other women beam with joy when they get the good news!




All facts and information provided in this article has been researched using biomedical, scientifically reviewed literature from sources such as MEDLINE, the National Center for Biotechnological Information (NCBI) and the Mayo Clinic. We have tried to incorporate a variety of scientific perspectives to provide you a comprehensive and unbiased overview of current knowledge in the field.


  1.  Fehring RJ, Schneider M, Raviele K. Variability in the phases of the menstrual cycle. Journal of Obstetric, Gynecologic, and Neonatal Nursing. 2006 May-Jun;35(3):376-84.
  2.  Suarez SS, Pacey AA. Sperm transport in the female reproductive tract. Human Reproduction Update. 2006.
  3.  Dunson DB et al. Day-specific probabilities of clinical pregnancy based on two studies with imperfect measures of ovulation. Human Reproduction. 1999. 14(7):1835-1839.
  4. Wilcox AJ. The timing of the “fertile window” in the menstrual cycle: day specific estimates from a prospective study. British Medical Journal. 2000;321:1259.
  5.  Wilcox AJ. The timing of the “fertile window” in the menstrual cycle: day specific estimates from a prospective study. British Medical Journal. 2000;321:1259.
  6. Jukic AM (2007). Life-style and reproductive factors associated with follicular phase length. Journal of Women’s Health. November; 16(9):1340-1347.
  7.  Thijssen A, Meier A, Panis K, Ombelet W. ‘Fertility Awareness-Based Methods’ and subfertility: a systematic review. Facts Views Vis Obgyn. 2014;6(3):113-23.
  8. Thijssen A, Meier A, Panis K, Ombelet W. ‘Fertility Awareness-Based Methods’ and subfertility: a systematic review. Facts Views Vis Obgyn. 2014;6(3):113-23.

1 Comment

  • Genevieve

    You’ve maagned a first class post