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Clearblue® Ovulation Calculator


Embed our ovulation calculator to enrich your fertility content.
Knowing the most fertile days in a cycle can increase a woman’s chances of conceiving and knowing the likelihood of ovulation on a specific day may help women understand their fertile window. This ovulation calculator tool estimates the days on which a woman is most likely to ovulate.
Currently, our tool only works for WordPress, but this plugin will be available on other platforms shortly.

What is an ovulation calculator?

An ovulation calculator estimates how likely a woman is to release an egg on a particular day in her menstrual cycle.

How does the ovulation calculator work?

The ovulation calculator takes the date the last period started and the average cycle length to estimate when a woman is most likely to ovulate. Results are based on information provided and on data from the following publication: Sarah Johnson, et al. Current Medical Research and Opinion (2018) DOI:10.1080/03007995.2018.1475348

How to use the ovulation calculator?

  1. The user enters the first day of the last menstrual period on the calendar.
  2. The user enters the average cycle length from the drop down list.
  3. The user clicks ‘calculate’.

How will results be displayed and what do they mean?

Once the data is entered and ‘calculate’ clicked, a calendar will be displayed showing the days on which ovulation is likely marked in purple together with a percentage. This is a percentage chance of ovulation on that day based on the inputted data.

Can I rely on an ovulation calculator?

An ovulation calculator estimates the potential ovulation days by taking the average cycle length and the date of the last period – basically the calendar method. It should be used for informational purposes only.
Detecting personal fertility hormones by using ovulation tests is a more accurate method to identify fertile days.
Ovulation tests are 2x more accurate than calendar method [1].

[1]: Study of 101 women in the UK comparing a simple calendar method to likelihood of conducting a test on LH surge day (2011).

How is an ovulation calculator different to a fertility calendar?

  • An ovulation calculator estimates the likelihood of ovulation happening on a particular day.
  • A fertility calendar indicates the days when sex is likely to result in conception.


This tool is provided by Clearblue.


  • Example of display in front-office.
  • Example of shortcode in a back-office page.
  • You can customize the display of the tool.


Installation from within WordPress

  1. Visit Plugins > Add New.
  2. Search for Clearblue® Ovulation Calculator.
  3. Install and activate the Clearblue® Ovulation Calculator plugin.

Manual installation

  1. Upload the entire clearblue-ovulation-calculator folder to the /wp-content/plugins/ directory.
  2. Visit Plugins.
  3. Activate the Clearblue® Ovulation Calculator plugin.

After activation

  1. Visit Tools > Ovulation Calculator.
  2. Configure the tool according to your needs.
  3. See below on how to display the tool on your website.

Usage : As a shortcode

Add the shortcode [clearblue-ovulation-calculator] within the content of any of your pages/posts.

Usage : As a widget

Visit Appearance > Widgets and drag and drop the Ovulation Calculator widget in the desired widget area.


May 5, 2022
This ovulation calculator plug in was quite easy to install. My client seems happy that their customers can now use it. We have not heard back feedback yet.
September 27, 2021
I plugged this tool into my website and I have only been getting good feedback since. It is very easy to use for the end user and installing it as well as setting it up is so easy! I definitely recommend to install it for any fertility-related content..
Read all 2 reviews

Contributors & Developers

“Clearblue® Ovulation Calculator” is open source software. The following people have contributed to this plugin.


“Clearblue® Ovulation Calculator” has been translated into 1 locale. Thank you to the translators for their contributions.

Translate “Clearblue® Ovulation Calculator” into your language.

Interested in development?

Browse the code, check out the SVN repository, or subscribe to the development log by RSS.



  • Fix translation integration
  • Fix encoding


  • Add translations


  • Fix ovulation calculation


  • Stable version of the plugin
  • English only