Ovulation calculator

Ovulation Calculator
When did your last period start?
E.g. 18/01/2020
Usually, how long is your cycle?
Cycles typically vary from 23 to 35 days
Estimate your ovulation day
likelihood of ovulating today
Due to your cycle length, unfortunately we can't estimate an ovulation probability. We recommend that you use a Digital Ovulation Test to accurately detect your most fertile days.
  *
Start of your last period
  20%
Likelihood of ovulating on this date
Change my informations
In partnership with Clearblue®.
Results are based on the information you have provided and data from the publication below: Sarah Johnson, Lorrae Marriott & Michael Zinaman (2018): “Can apps and calendar methods predict ovulation with accuracy?”, Current Medical Research and Opinion, DOI:10.1080/03007995.2018.1475348

What is ovulation calculator?

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

Our ovulation calculator will increase your fertility chances.
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.

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.

How to use the ovulation calculator?

  1. Enters the first day of the last menstrual period on the calendar.
  2. Enters the average cycle length from the drop down list.
  3. Clicks “Estimate Your Ovulation day”

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.
How ever, 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.