Mother and Baby

Ovulation Calculator


Best ovulation test kits

Try our ovulation calculator to discover your unique cycle and when the best time to conceive may be.

When am I ovulating?

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To maximise your chance of getting pregnant it can be best to look at the days you're most fertile as you can only get pregnant on the few days of each cycle around ovulation, when an egg is released.

On the ovulation calculator, the days shaded blue are the days your period is due – and a great tally for working out when it's time to take a pregnancy test.

How does your menstrual cycle work?

While the average menstrual cycle lasts 28 days, anything from 22 to 36 days is perfectly normal. 

Right now, your body is shedding a combination of the lining of your womb (called the endometrium) and actual blood. You won't know whether your egg has been fertilised for another month but can still do things to focus on your fertility, such as eating a healthier diet and reducing your alcohol and caffeine intake. 


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Your menstrual cycle explained

  • Week 2: The lining of your womb thickens ready for fertilisation, and eggs begin to mature in the ovary.
  • Week 3: This week, your levels of lutenising hormones (LH) and follicle stimulating hormone (FSH) will rise, stimulating the production of follicles in your ovaries. Usually, one follicle will become larger than the others and will produce the egg. That follicle will also start to produce oestrogen - the clever hormone that tells your body to start thickening the lining of the womb for implantation. If sperm is present at the moment of ovulation, or 24 hours after the egg is released, the egg may be fertilised.
  • Week 4: If fertilised, the egg will now travel from the fallopian tube to your uterus and divide into 16 identical cells. If the egg has not been fertilised, the egg is re-absorbed, hormone levels drop and your menstrual cycle begins again with your next period.

How to spot the signs and symptoms of ovulation

Some women can spot physical signs of ovulation occurring. Some symptoms include:

  • Cervical mucus: It’s best described as similar to egg white - slippery and clear.
  • Temperature: Your basal body temperature (BBT) rises about half a degree after ovulation has occurred. You can buy a special basal thermometer to help you chart when ovulation happens. Take the reading before you get out of bed every day to ensure it’s as accurate as possible.
  • Ovulation pain: Some women may experience Mittelschmertz or “Middle Pain”, as 'stitch-like' pain on one side or towards the bottom of the tummy. 
  • Ovulation bloating: Hormone changes during your menstrual cycle can result in slowed digestion and bloating during ovulation.

Conception and sex: How to boost your chances of conceiving  

Now you know when you're most fertile, make the ovulation calculator results work for you and boost your chances of conceiving no matter where you are in your menstrual cycle.

  • Have the best baby-making sex: To increase your chances of getting pregnant, is it advised to have sex around the time you are ovulating. In this case, you should have sex for the three days leading up to ovulation and possibly on the day you expect to ovulate, too. 
  • Top up on folic acid: 400mg of folic acid is recommended if you’re trying to conceive and into your first trimester. 
  • Eat a healthy diet: super-simple tweaks to your diet will provide your body the with fertility-boosting nutrients you need to grow a baby.
  • Keep it in perspective: Most couples having regular sex twice or more a week will get pregnant within a year. However, it can be hard to ignore the worry that there might be something wrong if you don’t get pregnant straight away. If you're concerned and it's been over a year with no luck, visit your GP. 

How to use ovulation test kits

Ovulation calculators (also known as fertility calculators) are a good indicator of where you are in your menstrual cycle, however, every person is unique and so is their cycle, so it's important to take the results with a pinch of salt. The results may also be skewed if you are unsure when exactly your last period was, you have just come off the pill or your periods are irregular. If you’ve been trying for a while, talk to your GP. 

One to two days before ovulation occurs, the body produces a surge of the luteinizing hormone (LH) which can be detected in urine. Ovulation predictor kits (OPKs) look for this surge and alert you to its presence - digital OPKs will display a symbol such as a smiley face.

This means it is likely you’re about to ovulate, so it’s recommended you have sex on the day of the surge, as well as the two days after. Play it safe by adding one more day onto this, just in case you’ve ovulated a day later than expected.

There are other ways of tracking ovulation, including a number of helpful apps. These apps can help you track your cycle and learn more about your ovulation patterns allowing you to get to know your body better from your phone or tablet. 

Support when trying to conceive

Trying to conceive can be an emotionally draining experience, not just for you, but for your partner, too. Fertility Network UK offer support groups where you can share your ttc journey with others who are going through the same experience. You can also find other support lines to help with stress and anxiety here. 

Brought to you by Mother&Baby

Our mum journalists work closely with our medical panel of midwives, doctors, paediatricians, child development specialists, parenting experts and many other field specialists to ensure the educational content you find here is up-to-date with the latest evidence-based medical information and accepted health guidelines. 

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