How an ovulation calculator can help you conceive 

Are you and your partner on the journey to finally start a family? Becoming knowledgeable and empowered about your fertility is one of the most important things you can do to increase your chances of conception. Our ovulation calculator can assist in your understanding about your menstrual cycle, but you may also like to take this to the next level and get knowledgeable on your natural fertility indicators (also known as fertility awareness) to really understand when you are most fertile. In this blog post, we’ll explore how our ovulation calculator and fertility awareness can help you conceive and provide tips for maximising its effectiveness.

Please note:

The fertility calculator is not to be used for contraception. 

First day of the last menstruation:

Days (on average 28 days, if you do not exactly know how long your cycle is)



= first day of the menstruation
= probable ovulation
= rather a girl
= rather a boy
= fertile days
= highly fertile days

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How to use the ovulation calculator

Your LMP, or last menstrual period, is the starting point for calculating your ovulation.


To use our ovulation calculator, you need to enter the date of your last period and the average length of your menstrual cycle. The calculator will then give you an estimated date range for when you're likely to ovulate.

Ideally, and for that extra accuracy, use an app which will allow you to add in your natural fertility indicators, so you can really see when you are becoming fertile.

It's important to remember that every woman is different and that there's no one-size-fits-all approach to conceiving.

Conception and fertilisation process – when does conception occur?

Conception, also known as fertilisation, is the process by which a sperm and egg fuse together to form a zygote. The zygote then develops into an embryo and eventually a baby in the womb. Ovulation is the release of an egg from the ovary and an egg is capable of being fertilised between 12-24 hours after ovulation, so just for a very short window! The good news, however, is that sperm can live for approximately 5 days in the vagina and therefore any sex that occurs in the 5 days prior to ovulation can result in a pregnancy.

There are many factors that can influence conception, including age, health, lifestyle, and medications. Many couples who are trying to conceive use ovulation calculators to help them predict when ovulation will occur alongside tracking and understanding the menstrual cycle.

When is the best time to conceive?

Ovulation occurs when an egg is released from the ovary. This may occur on day 14 of a 28-day cycle. However, if you have a longer or shorter cycle then ovulation may occur earlier or later. We also know that ovulation doesn’t always occur on the same day each month. All of these variables can make it difficult to understand when ovulation may occur for you, and that's where using an ovulation calculator and fertility awareness comes in handy.

To use an ovulation calculator, simply enter the first day of your last period into the calculator, and it will give you an estimate of when you're likely to ovulate. From there, you can plan accordingly and have sex around that time to increase your chances of conceiving. However, it is important to be aware that the ovulation calculator assumes that you are ovulating mid-cycle, and this may not be fully accurate, this is where fertility awareness steps in to help you understand more.

There are recognised natural fertility indicators that you can look out for. Your body temperature may rise slightly the following ovulation, and you may notice changes in your cervical mucus. This mucus becomes thinner and more slippery prior to and during ovulation, and it may resemble raw egg whites. The position of your cervix also changes throughout the cycle, and whilst this is more difficult to observe, it can be useful. A cervix that is low in the vagina and feels firm (like the end of your nose) indicates that you’re not fertile but a cervix that is higher in the vagina and soft (like your earlobe) is telling you are in your fertile window. Keep track of these changes each month, so you can better predict when you'll be most fertile. Then, have sex during your fertile window to increase your chances of conceiving.

While an ovulation calculator can give you a good idea of when you should try to conceive, there's no guarantee that you'll get pregnant. There are many factors that come into play, including egg and sperm health.

When is the best time to conceive with a girl or boy?

The sex of your baby is determined by the chromosome carried by the sperm that fertilises the egg. So, if a sperm carrying a Y chromosome fertilises the egg, you will conceive a boy, and if an X chromosome-carrying sperm fertilises the egg, you will conceive a girl. There's no scientifically proven accurate way to time this to choose the sex of your baby. 

Tips on how to conceive twins naturally and what may increase your chances of having twin

If you're hoping to conceive twins, there are a few things that increase your chances. First, you should know that twins are more likely to be conceived by mothers who are over the age of 35. Additionally, women who have already had twins or multiple births are more likely to conceive twins again. There are also certain medical treatments that can increase your chances of conceiving twins, such taking fertility drugs during IVF. 

However, it is important to recognise that, whilst it might be lovely to have twins, there are certain risks associated with having a multiple pregnancy. These risks can include developing a blood clot, anaemia, liver problems, increased pregnancy loss risk, premature birth, and labour complications. If you do conceive twins, you can be reassured that your medical team will keep a close eye on you to reduce the risk of these complications occurring. 

So, in summary:

  • Try using our ovulation calculator to pinpoint your most fertile days. This can help you time intercourse correctly for when you're most likely to conceive. 
  • Start observing and monitoring your natural fertility indicators and use this information along with your cycle dates to identify your fertile time.
  • Have intercourse frequently leading up to ovulation, ideally every 2-3 days throughout the cycle. The more times you have sex during your fertile window, the better your chances of conceiving.

Reviewed by:

Kate Davies is an independent fertility and women's health nurse consultant and director of Your Fertility Journey Ltd. For more information, see here

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