Mother and Baby

Ovulation Calculator


Best ovulation test kitsTrying to conceive (TTC)? Work out when you're most fertile and when is the best time to get pregnant with our ovulation calculator.

Using our ovulation calculator is easy, all you need to do is enter the first day of your period.

Then we need to know the average cycle length of your menstrual cycle so we can calculate the window of time when you're most fertile. While the average menstrual cycle lasts 28 days, anything from 22 to 36 days is perfectly normal, so pop your number in and press 'submit'.

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How to interpret your results 

The asterisks show the day you're ovulating. And all those days that are ticked? That's when you're at your most fertile, so this is the best time to get pregnant.

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 to boost your chances of conceiving 

To maximise your chances of getting pregnant during the few days around ovulation, you'll need to get your fertile eggs and your partner's sperm together as much as possible. Read more about the best expert tips to try and help you conceive here. 

Your menstrual cycle explained

Pregnancy testNow you know when you're most fertile, make the ovulation calculator results work for you and figure out what you need to do to boost your chances of conceiving no matter where you are in your menstrual cycle.

For a pregnancy to occur, an egg must be fertilised and then successfully implanted in the wall of the uterus, which has been thickening up in preparation. It can’t be fertilised in the ovary, so ovulation needs to happen before natural fertilisation is possible. If the egg isn’t fertilised, the body sheds the lining of the womb, along with the unfertilised egg and a period begins, along with a new cycle. 

Week one - your period is due

If you've got your period (when you were really hoping it wouldn't happen) stay positive. Just think, if you do conceive this month, this will be considered week one of your pregnancy. 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. 

But if you think there could be some bad habits that are stopping you getting pregnant, this is a great week to make those healthy resolutions, including taking folic acid, which has been proven to protect your future baby from spina bifida, and getting your body as healthy as it can be.


A message from our partner:

"A supplement such as Proceive Conception can also help tick this box of trying to get pregnant, by providing carefully tailored nutrients for both women and men, after all it takes two. Proceive Men provides 26 nutrients including selenium to support sperm production and zinc to support fertility. While Proceive Women provides 28 tailored nutrients including folic acid in the active Methylfolate form, Vitamin B6 for hormone regulation and Vitamin B12 has a role in the process of cell division."

Focus on eating a balanced diet, with lots of nutrients, including zinc, and avoiding too much caffeine (no more than three cups of coffee a day). Now is also the time to shake off those vices - if you smoke, try to quit, and cut down on alcohol. 

And if you've missed your periods due date? While it's never great to obsess over the early signs of pregnancy and when to take a pregnancy test, being aware of them is a good idea.

Week two - You’re almost in your most fertile week 

Focusing on what you both eat in this week will help ensure you're on top form as you come into your most fertile time. Find out the foods that boost his sperm count and help your fertility.

Now is the time to turn down the heat, literally! Discourage your partner from taking steamy hot showers or soaking in a hot bath, as this can affect sperm quality. It's also a good idea to turn off your electric blanket and stop sitting with your laptop on your lap. It might sound crazy, but studies have shown prolonged and excessive heat can actually slow down sperm collection. 

Remember, that TTC sex shouldn't just be about that most fertile week. It's important to keep the connection alive all through the month so sex never feels like a chore. We've got some great tips on the best sex positions for getting pregnant. And if your heart's set on having a little girl, it may be an old wive's tale but there is a theory that conceiving before your fertile week could help.

Week three - You’re in your most fertile week 

You're most fertile, so now's the perfect time to enjoy plenty of baby making sex - this is the best time to get pregnant. And while, yes, you really want to get pregnant right now, remember you want a baby with him, so it's worth making sure TTC doesn't take over your relationship.

This week, hopefully, your partner's sperm will meet your egg and your baby will start to form. Our menstrual cycles really are incredible, and 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.  

It might sound as simple as egg - meet sperm, but your partner's sperm actually have to make a ten-hour journey from your vagina, through your cervix and up to the fallopian tube where it can hopefully penetrate your egg. If you're having sex on your most fertile days, hopefully in the 24 hours after the egg is released, one of the 250 million sperm your partner will have released will burrow through the egg's outer membrane.

Week four - You’re just out of your most fertile week 

Obviously trying to conceive is top of your agenda right now, but keep in mind that your life isn't all about getting pregnant and that you're not the only couple going through this. The 10 things you only know if you're trying to conceive should really ring true.

That said, if you're needing an excuse to have a health overhaul, this could increase your chances of conceiving, too. If you've decided to take your basal temperature to use alongside the ovulation calculator, now's the time you should be seeing a change.

The good news is, if you have had sex on the right days, hopefully, week four could mean you've conceived! Your egg will now travel from the fallopian tube to your uterus and divide into 16 identical cells.

Best ways to track ovulation 

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. Read more about our round-up of the best fertility apps.  

It's really important we get to know our bodies when trying for a baby and get to grips with ovulation. There are certain signs and symptoms of ovulation to recognise that allow some women to know exactly when they are ovulating without the need for test kits or calculators. From tender breasts to an increased sex drive - here are five symptoms that are telling you your body is ready to conceive. 

Read more about the different ways to track ovulation here

How do I know when I'm fertile? 

Woman holding stomachSome 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 so you can predict your fertile window in the following months. You’ll need to take the reading before you get out of bed every day to ensure it’s as accurate as possible.

Read more about the signs and symptoms of ovulation here

Are ovulation calculators accurate? 

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. 

It may be worth purchasing an ovulation test kit if you really want to be sure, which promises to be 99% accurate. 

Check out all the different ways you can track your ovulation, here

I have irregular periods? How can I work out when I'm ovulating? 

Of course, if your periods are not regular, using our ovulation calculator gets a little harder. We recommend going to speak to your GP to get some medical advice about your periods if you've been trying for a while, just to be sure this is not affecting your fertility. For more information and support, visit our dedicated Trying To Conceive channel.

Ovulation facts 

  • The sound of your voice changes during your period: Researchers suggest that the change of female reproductive hormones actually alter your vocal cords, thus changing the sound of your voice.
  • The average woman has more than 400 periods in her lifetime: Between the average woman's first cycle and menopause, you can expect over 400 times of the month, according to an article published in the scientific journal The Lancet.
  • The amount of blood you lose is around 16 tablespoons: Per period, the amount you bleed equates to 16 tablespoons or roughly two shot glasses, on average
  • You may spend more money during your period: Researchers from the University of Hertfordshire found that women spent more money and shopped more impulsively while menstruating than during other phases of their cycle.

Read more surprising period facts, here

Ovulation pain

We're all well aware of how painful our periods can be every month, but did you know that some women also experience pain during ovulation too (as if period pain wasn't bad enough)? 

Ovulation pain is known as Mittelschmertz which is a German word meaning “Middle Pain” caused when the ovary released an egg. Some women have referred to this pain as 'stitch-like' pain on one side or towards the bottom of the tummy. 

Find out more about ovulation pain including the signs, symptoms, remedies and expert help here.

When and how often you should have sex during ovulation? 

Couple trying to conceive To increase your chances of getting pregnant, is it advised to have sex around the time you are ovulating.

For a lot of couples who are trying to conceive, sex can begin to feel like a chore - especially if you've been trying for a while and are fixated on results, so it's important to have sex which doesn't feel like a 'baby-making mission'. Especially as stress can be counterproductive when trying to conceive.

If you chart your basal body temperature, you can know the approximate day you ovulate each month. In this case, you should have sex for the three days before you expect to ovulate and possibly on the day you expect to ovulate, too. 

However, you should still have sex throughout your cycle, just to keep the sperm quality in tip-top shape. You also need to provide time to enjoy sex without a baby-making mission attached.

Support when trying to conceive 

It's common to feel stressed and down when trying for a baby, as struggling to conceive can send you and your partner on a real rollercoaster of emotions. To help women through the difficult and often all-consuming journey they can experience while trying to conceive or going through fertility treatment, there is support out there. Fetility 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

Read more: Find out more about reducing stress when ttc here. 


You've used our ovulation calculator - what next? 

You’ve used our ovulation calculator – but what do you do now? It’s normal to feel stressed at the mere mention of your ovulation dates. But there are lots of simple steps to help increase your chances of conception.

  • Have the best baby-making sex: You’ve found the days you should be doing it, highlighted them in your diary and let your partner know date night is on. But what about the actual sex? Discover how to have the best baby-making sex to improve the likelihood of conception.
  • Top up on folic acid: Up until now the only vitamin hit you swore by was a Berocca after a big night out. So murmurs of supplements and fertility may be sending you into guilt overdrive. The advice goes like this: a 400mg of folic acid is recommended if you’re trying to conceive and into your first trimester. Found out how to get folic acid into your daily diet. 
  • Make food work for you: You’ve heard the spiel about a balanced diet, but aren’t ready to bin the entire contents of your fridge or turn your back on the work birthday buffet. All you need are some super-simple tweaks to your diet to provide your body with fertility-boosting nutrients you need to grow a baby.
  • How to help him: Trying to conceive can be an emotionally draining experience, not just for you, but for your partner, too. There’s a chance he’s feeling the strain and if it’s putting stress on your relationship, follow our fertility relationship guide. Or, if his confidence is taking a battering, keep it and his mojo up.
  • Keep it in perspective: Most importantly, relax about it. 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. 

- Reviewed by Dr Helena Watson on 6th June 2020

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