Knowing when you are ovulating increases your chances of getting pregnant. But as many of us know, this isn’t always easy especially if you have ​​Polycystic Ovarian Syndrome (PCOS). With PCOS, the timing of your ovulation is likely to vary from one cycle to the next and you may also have infrequent periods, making it impossible to know exactly when ovulation occurs. In fact, clinical studies show that 70% of women don’t ovulate in the middle of their cycle, and can ovulate at a different time from cycle to cycle, even if they are always the same length[1].

We know this can be a struggle, especially if you are trying to conceive! To help, we created the OvuSense Ovulation Calculator which will help you work out when you should try to conceive and recommend the best OvuSense product if you are looking to take more control over your fertility. The quick and easy calculator asks for some information about your cycles - including average length and date of last period - before giving you your ovulation results. 

Understanding The Ovulation Calculator & Results

Have a few questions about the calculator and potential results? To help clear up any confusion we’re answering some commonly asked questions around your cycle and fertile window, as well as outlining the different OvuSense products you may be recommended to try (OvuFirst, OvuCore, OvuSense Pro).

What's the difference between a 'regular' and 'irregular' cycle?

Your 'cycle' is the number of days from the start date of one period to the start date of your next period. A ‘normal’ menstrual cycle is 28 days in length, day 1 being the first day of your period. However, in reality, very few women have a regular 28-day cycle. A cycle may vary from 25-35 days in length, however, for women suffering from hormonal conditions such as PCOS, cycles can be much longer. You may have irregular periods if the time between each period starts to change or the number of days that your period lasts varies a lot.

When is the Fertile Window?

Your fertile window is governed by two important factors: how long an egg remains fertile once it’s ejected from your ovaries, and how long sperm can survive in your body. An egg survives up to 24 hours after you’ve ovulated, while sperm can survive for up to five days in the body, so depending on where the two people involved fall into that range, you have a fertile window of around six days in each cycle.

Identifying Your Fertile Window

Everyone is different, and that means that there’s no universal schedule telling you when your fertile window is – you have to look at your own body to learn the answers and learn when you ovulate. For the average woman, ovulation happens around sixteen days into their cycle, as measured from the first day of her period, but it can be anywhere between eleven and twenty-seven days into the cycle.

If you have PCOS or other fertility health issues, it can be even more irregular, or you may experience menstrual cycles without ovulating at all. Any kind of irregularity in your cycle makes it all the more important to take advantage of those times when you do ovulate, which means careful tracking of your cycle to spot the key signs that give you a clue when you’re in your fertile window.

Recommended OvuSense Products

After your results come in, the calculator will share the following details about your next cycles:

  • When your next period should begin
  • The start of your next fertile window
  • When you are likely to ovulate
  • The end of your fertile window

Having this information will allow you to take back some control of your fertility journey. However, as some of you know, you may still need some additional help when trying to conceive. This is where OvuSense and tracking for ovulation can come into play. There are various products to try regardless of where you are in your fertility journey. Below are the different sensors that could be recommended based on your results, as well as when and how you should be using them.


If you have regular periods and your cycles are 24-35 days long on average, our OvuFirst sensor is designed just for you. OvuFirst’s best-in-class accuracy gives you a better chance of getting pregnant more quickly. By reading your unique cycle pattern, it provides a full 8-day window telling you when you should try and conceive. You can wear the OvuFirst sensor on your arm or wrist each night and download the data each morning to our free OvuSense App. The OvuSense App then provides a real-time chart and clear fertility messages.

Example response from calculator: If you've been having unprotected sex for 3 months already you should consider using our OvuFirst product. That's because you may well now be in the 70% of women who don't ovulate regularly in the middle of your cycle. OvuFirst really helps you understand exactly when to try and conceive by confirming your 8-day fertile window. It uses a special algorithm that makes this confirmation more accurate with every cycle.


If you have irregular cycles or have been diagnosed with PCOS, the OvuCore sensor is designed just for you. OvuCore predicts your ovulation 24 hours in advance using information from your current cycle. Understanding your unique cycle pattern gives you a better chance of getting pregnant more quickly, even if you have irregular cycles. Insert the OvuCore sensor in your vagina each night, take it out in the morning and download it to our free OvuSense App. The OvuSense App then provides a real-time chart and clear fertility messages. OvuCore uses our revolutionary patented OvuSense technology trusted globally for over 10 years. Unlike other products, OvuCore is a class II medical device which means we have to prove what we claim through externally reviewed clinical studies.

Example response from calculator: You should consider using our OvuCore product, which helps with irregular cycles by providing you with a prediction of ovulation using the current cycle data. Clinical studies have shown it gets this prediction right 96% of the time[2]. It will then go on to confirm the exact day of ovulation with 99% accuracy[3].

OvuSense Pro

If you're already talking to an OB/GYN or specialist, or plan to see one about your fertility or pregnancy issues, our OvuSense Pro clinician portal is designed for you and your OB/GYN or specialist. OvuSense® Pro allows you and your OB/GYN or specialist to remotely access detailed information about your cycles through an online portal. It provides a unique analysis helping screen for common reasons why you may be struggling to conceive, and monitor medication or treatment you receive. Join the OvuSense family today and choose OvuSense Pro if you're already talking to an OB/GYN or specialist, or plan to.

Example response from calculator: Because you're seeing a doctor if you decide to buy you should consider adding OvuSense® Pro to your purchase of OvuCore. OvuSense® Pro allows you and your doctor to remotely access detailed information about your cycles through an online portal. It provides unique analysis helping screen for common reasons why you may be struggling to conceive, and monitor the medication or treatment you receive to see how well it's working.

Get Started Today!

Don’t wait to predict your upcoming fertile window and try out our new OvuSense Ovulation Calculator today! The OvuSense™ Fertility Monitoring family is designed just for you, wherever you are on your journey. Our OvuFirst and OvuCore sensors provide the most accurate answers you need now, to help you get pregnant faster.


[1] Baird D, McConnaughey D (1995); Lenton EA, Landgren BM (1984a); Lenton EA, Landgren BM (1984b)

[2] The key publication outlining the accuracy and positive predictive value of advance prediction of ovulation was shown at the 2014 ESHRE meeting: Papaioannou S, Delkos D, Pardey J (2014).

[3] The accuracy of ovulation confirmation by OvuSense is based on the data set originally published at the 2013 ASRM meeting as a quality index: Papaioannou S, Aslam M (2013), and developed in [2]