Calculate the fertile days

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.
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Start of your last period
  20%
Likelihood of ovulating on this date
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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

Fertile days may vary from woman to woman, depending on the cycle. So, if you know your cycle, you can predict the days that are most fertile, as well as the date of your next period.

If you have a steady cycle, it is easy to calculate your fertile days.

To achieve pregnancy, the man’s sperm must come into contact with the woman’s egg. This means that intercourse must take place during the days of ovulation.

Fertile days may vary from woman to woman, depending on the cycle. So, if you know your cycle, you can predict the days that are most fertile, as well as the date of your next period.

If you have a steady cycle, it is easy to calculate your fertile days.

Note that the fertile window is very small – a woman has about 3 very fertile days – and it is the only time a woman has increased chances of being able to conceive.

Ovulation takes place 14 days before the next period. So, in a 28-day cycle, ovulation takes place on day 14. The 3 days before and after the woman’s ovulation are the ones when she is most likely to conceive. In spite of this, intercourse that takes place up to 5 days before ovulation may lead to fertilization.

The three main stages of the menstrual cycle are pictured in the image above: the day marking the start of the cycle, the fertile days and the earliest possible a pregnancy can be detected by certain tests.

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