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Ovulation Calculator Apps

Whether you’re planning to start a family in the near future, checking the length of your cycle for health reasons or simply interested in understanding your body better, there are lots of apps available for Android, Apple and Windows devices that promise to calculate, identify and even predict when you ovulate with a few simple inputs.

They’re not all equal, and if you’re forced to make a choice between all the apps available you need to know how effective they are, and what method they’re using. Making an informed decision requires information, and OvuSense is here to deliver some.

Counting Calendar Days

One thing all apps will ask for are the dates of your last period – the first day of your cycle is the first day of bleeding, and this is vital data. If you have an extremely regular period, this alone could be enough for the app to give you an accurate indication of when you’re due to ovulate but for the majority of people it will require more input.


Some apps will recommend looking at your saliva under a microscope! It seems unlikely but this can be an ovulation indicator as well. If you can see a fern pattern, like frost on a window, this is caused by the same hormonal changes that bring on ovulation, and so it has valuable information about your menstrual cycle.

Cervical Mucus

The quality of your cervical mucus changes over the course of your cycle – when you’re not fertile it forms a barrier to prevent things passing through your cervix, but when you ovulate, sperm need to cross this barrier! You can tell when ovulation is approaching, as your cervical mucus changes: it becomes less sticky, more transparent, and resembles egg white.

Basal Body Temperature

One of the more accurate methods you have of telling when you’re ovulating is your basal body temperature – it’s a method that’s been known and used for decades. Long before apps and computer programmes, people would chart their temperature readings on a graph, and have to work out manually when the pattern shows they were ovulating.

Your BBT is the low minimum temperature your body rests at during a night’s sleep. Prior to ovulation, it often dips, followed by a noticeable rise in the three days following.

Many apps ask for your temperature so they can make predictions, but their output is only as good as your input! Getting an accurate read of your BBT is tricky, as from the moment you wake up, it begins to be swamped by your metabolism warming your body up for the day. You have to do it first thing, moving as little as possible. If you find it hard to function before coffee in the morning, this could be a technical step too far!

OvuSense has an advantage here, as our app and algorithm comes with a specialised sensor which takes your temperature overnight for the most accurate data possible.


In general, the more indicators an app asks for, the better results it can give you. You might want to make an exception for OvuSense though, which bases its results on the best measure possible, and uses specialised technology to get that data for you.

Find out more about core temperature technology and fertility here