Ovulation Calculator

Knowing when you are ovulating increases your chances of getting pregnant.

This isn't easy to predict and the OvuSense® ovulation calculator will help you work out when you should next try to conceive and recommend the best OvuSense product if you are looking to take more control over your fertility.


Understanding Your Ovulation Calculator Results

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. If that number of days is about the same from one cycle to the next (within 1-4 days) and more often than not you have almost no variation in the number of days then you have 'regular' cycles and it's easy to calculate your average number days in your cycles. If the number of days in your cycles are 5 days or more from one cycle to the next, and particularly if you find that cycles rarely have the same number of days then you have a degree of 'irregular' cycles. Don't worry though, most women can conceive naturally even if they have irregular cycles, they just need a little more help.

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.

[1] 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).
[2] 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 [1]
[3] Internal Fertility Focus side by side study of OvuFirst and OvuCore Sensors (2021), documented as a class II medical device in the notified body reviewed CE Certificate Technical File.