Ovulation calculator

Knowing when you ovulate, and how your menstrual cycle works, can help you identify the time when you're at your most fertile – and therefore most likely to conceive. This means that, when you're trying to get pregnant, you can concentrate your baby-making efforts on the days when the odds are in your favour.

Use our quick and easy tool below to find out the days each month when you are most fertile.

Simply put in the date your last period started on, and the length of your menstrual cycle (this is the number of days from the start of one period to the day before the next one). Once we've done the calculations for you, the calendar will highlight the days when you're most likely to conceive.


You're at your most fertile during the days leading up to ovulation, and on the day itself. To maximise your chances of conceiving, use our calculator to work out your most fertile dates over the next six months.

Enter the date your last period started

How long is your menstrual cycle?

My Ovulation Calendar

First day of your period

Most fertile days

Contrary to what some biology textbooks may tell you, most women do not ovulate like clockwork on day 14 of a 28 day cycle. Menstrual cycles can last between 24 and 35 days, and ovulation can happen anywhere between 10 and 16 days before your period begins.

If your periods are irregular (if your cycle varies in length each month, or is consistently shorter than 24 days or longer than 35 days) it might be a bit trickier to work out when you're ovulating – but it's not impossible!

Look out for signs of ovulation, such as changes to your body temperature, cervix and cervical mucus and how you feel in general. Keeping track of any changes throughout the month can help you recognise your own symptoms around ovulation and better understand the length of your cycle, and at which point you are most fertile.

It's recommended that, if you’re trying to get pregnant, you should be having sex throughout your cycle – every other day is the optimum. However, the best time to conceive is in the two days before ovulation (usually days 12 to 14) in preparation for the egg being released.

Before you start, find out how you can prepare your body and mind for conception, throughout the month, to improve your chances of getting pregnant at the prime time.