Ovulation Calculator

Our ovulation calculator and fertility calendar show you when ovulation will likely happen, and when you're at your most fertile. Knowing your fertile days can help to improve your chances of getting pregnant. Every woman's menstrual cycle is unique, so discovering your own fertile window will help you work out when you have the best chance of conceiving a baby.

What is ovulation?

Ovulation is when your ovaries release an egg. It usually happens about two weeks before your period starts.

The egg moves from the ovary to the uterus through the fallopian tubes. It lives for between 12 to 24 hours after ovulation. If during this time the egg meets sperm, you can conceive a baby.

When am I most fertile to conceive?

Your fertile window is the best time of the month to try for a baby, based on your menstrual cycle. It includes the five days just before ovulation, and the day of ovulation itself.

Sperm can live in your body for a few days, so having sex in the days leading up to ovulation will improve the changes that the egg meets sperm once it is released.

How can I calculate my fertile days?

The Ovulation Calculator will ask you to enter the first day of your last menstrual cycle and how long your cycle usually lasts. The length of your cycle is the number of days from the first day of last period to the day just before your next period starts. The average cycle length is usually around 28 days.

The ovulation calculator will count back 14 days from the day you expect your next period to start and tell you which day you are likely to ovulate.

Your fertile window includes the day you ovulate and the five days before. The highest chances of conceiving are during the last three days of this time frame.

Our calculator will create a personalised fertility calendar showing your full fertile window each month for the next six months.

This way you'll know your upcoming fertile days, and when your baby will be due if you do conceive. So you'll have all the information you need to start planning your pregnancy.

NOTE: This tool provides approximate dates only and assumes a regular menstrual cycle. The timing of your fertile window can be unpredictable, even if your cycles are usually regular.

What are the signs of ovulation?

You can also notice changes when ovulation happens such as:

• Rise in basal body temperature
• Cervical mucus is the texture of egg whites
• Breast tenderness
• Mild cramps or twinges in the abdomen
• Very mild spotting
• Heightened sense of smell
• Increased sex drive
• Changes in appetite or mood
• Bloating

What if my menstrual cycle is irregular?

If your cycles are irregular, you may have trouble pinpointing your day of ovulation based on this calendar alone. Find out about ovulation predictor kits (OPKs), or read more ways to predict ovulation using your basal body temperature, checking your cervix for changes or observing your cervical mucus.

Learn more about ovulation and how your menstrual cycle works.

Should I only have sex when I'm most fertile?

Planning sex for your fertile window can be helpful to get pregnant, but it can also take the fun spontaneity out of sex. So, if you're able to, have sex every two to three days throughout your cycle. This will give you the best chance of conceiving because this way, no matter when you ovulate, there will be sperm waiting to fertilise your egg as it's released.

Can conceiving at certain times increase my chances of having a boy or a girl?

No. There is a theory – known as the Shettles method – which suggests that:

• having sex during or after the day of ovulation is more likely to conceive a boy
• having sex from the end of your period to three days before ovulation is more likely to conceive a girl

However, there is no evidence to support this theory.

Can conceiving at certain times increase my chances of having twins?

No, there's no way to increase the chances of having twins. It may be more likely to happen for you if you're having fertility treatment, are over 35, or if twins run in your family.