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Ovulation calculator

ovulation Window of opportunity

When is the best time to conceive?

Understanding your menstrual cycle and the date that you are likely to be ovulating can increase your chances of conceiving. Ovulation usually happens around two weeks before your period starts1, and you are most likely to conceive if you have plenty of sex in the days prior to this.

Common signs of ovulation

As ovulation approaches you may notice some physical changes. These include1:

  • An increase in vaginal mucus, along with a change in consistency which may make it look like egg white
  • A slightly raised temperature
  • Abdominal pain
  • Tender breasts
  • Spotting
  • Feeling bloated

Charting your temperature

Prior to ovulation your body temperature drops a little, then rises by around 0.2°C after ovulation2. Recording your basal body temperature (this is your resting body temperature) with a special thermometer first thing in the morning, before you get up or even speak, can help establish when you’re most fertile. Remember, it’s the few days before your temperature rises that are important.

Ovulation kits

Alternatively you can buy ovulation kits from larger chemists or supermarkets. These test for raised levels of luteinising hormone (LH), which can be detected in your urine just before ovulation3.

Use our ovulation calculator to discover the best time to conceive

To get the most accurate date, you need to know the average length of your menstrual cycle and the day that your last period started. Our ovulation calculator can help you to predict when you are going to be most fertile.

When was the first day of your last period?

Adjusted cycle length

If your cycle is longer or shorter than 28 days, please change the number below.

View references

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1. NHS. (2014). How can I tell when I’m ovulating? Available from: https://www.nhs.uk/chq/Pages/982.aspx?CategoryID=50 [Accessed July 2015]

2. Fertility Education & Training. (2011). Charting your fertility cycle. http://www.fertilityet.org.uk/pdfs/Charting-Your-Fertility-Cycle.pdf [Accessed July 2015]

3. Patient. (2015). Natural family planning. http://patient.info/health/natural-family-planning [Accessed July 2015]

Last reviewed: 4th July 2016

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