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Ovulation Calculator


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Trying to conceive (TTC)? Work out when you're most fertile and when is the best time to get pregnant, to increase your chances of getting pregnant with our easy-to-use ovulation calculator.

All you need to do is put in the first day of your last period. 

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

What to read next:

How soon after coming off the pill can you get pregnant?
10 trying to conceive tips the experts want you to know
6 Factors that increase your chance of having twins or multiples

What does the calculator mean and when are your most fertile days?

The asterix 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.

Boost your chance of conceiving

Now 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 - and to find out when is the best time to get pregnant in your cycle.

Your period’s due - week one

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. Focus on eating a balanced diet, with lots of nutrients, including zinc, and avoiding too much caffine (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 that period isn't showing up? While it's never great to obsess about the early signs of pregnancy and when to take a pregnancy test, being aware of them is a good idea.

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

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. And if your heart's set on trying to get pregnant with a girl, there is a theory that conceiving before your fertile week could help.

You’re in your most fertile week - week three

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 partners 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, which stimulates the production of follicles in your ovary. Usually one folicle 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 eggs outer membrane.

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

While trying to conceive is top of your agenda right now, 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 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 when 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 concieved! Your egg will now travel from the fallopian tube to your uterus and divide into 16 identical cells.

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 about you 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.

19 facts about ovulation: 

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The average woman’s’ cycle is 28 days, but your cycle can be anything from 22 to 36 days long. Ovulation normally happens about two weeks before your next period, so if your cycle is 28 days, you will ovulate around day 14. Work out when you are ovulating by using our ovulation calculator. 
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Your egg lives for up to 24 hours after leaving your ovary, so if you are having sex around your most fertile days, you’ll have the best chance of conceiving. 
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That said, your partner’s sperm can live for up to five days, so it’s a good idea to also have sex before ovulation occurs if you are trying to conceive. 
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Your partner will release around 250 million sperm during ejaculation, however only around 400 of these sperm will make the ten-hour journey from your vagina, through your cervix and up the fallopian tube, where it can penetrate the egg. Only one can burrow through your eggs outer membrane. 
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Ovulation can be affected by a number of different things including stress and illness. If you’ve been trying for a baby for a while, it might be time to take a look at your job stresses, or workout routine. 
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The sex of your baby is actually determined from the moment your partner’s sperm meets your egg – if the sperm is carrying a Y chromosome, you’ll have conceived a boy and if it’s an X chromosome, it’ll be a girl. 
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Every woman is born with millions of immature eggs – half of these will be absorbed by your ovaries before you reach adolescence, the other half will sit waiting for your ovulation cycle to begin. Only 300 to 500 of these eggs (medically referred to as oocytes) will become mature eggs in your lifetime.  
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You can have a period even if you haven’t ovulated and you can ovulate without having a period. 
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Some women experience some bleeding as their fertilised egg burrows into the lining of their womb, this is called implantation bleeding and can often be confused with a period. Here's how to tell the difference between implantation bleeding and a period
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If an egg is not fertilised by a sperm during the ovulation period, it will disintegrate and be absorbed into the lining of the uterus or pass out with the menstrual flow. 
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Ovulation happens thanks to two different hormones – during the most fertile week of your cycle, your levels of lutenising hormones (LH) and follicle stimulating hormone (FSH) will rise. This stimulates the production of follicles in your ovary. 
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Each month, one follicle will become larger than the others and produce an egg. Usually only one egg will be released during each cycle. This follicle will also start to produce oestrogen, which tells your body to start thickening the lining of the womb for implantation. 
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Once the egg has been released, the same (now empty) follicle will produce another hormone – progesterone, which prevents the release of any more eggs this cycle. The empty follicle is medically referred to as corpus luteum. This level of progesterone remains high enough to prevent any more eggs from being released for the next 12 to 16 days, after which your cycle will start again. This is the same horomone that is in birth control pills. 
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Your egg is smaller than the head of a pin when it is released during ovulation. 
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Although a lot of women do not experience any physical signs of ovulating, one in five will experience lower abdominal pain, known as mittelschmerz – a German word meaning ‘middle pain’. 
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Another physical sign you are ovulating is a clear, somewhat elastic discharge in the days leading up to ovulation. It might sound gross, but try stretching it between two fingers so you know what to look out for each month. 
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If you want to be really sure when you are ovulating, monitoring your basal body temperature (BBT) is a good indicator. Your basal body temperature averages around 36.1-36.4°C before ovulation, and rises to between 36.4-37°C after ovulation. The downside to this method is that your body temperature changes 12 to 24 hours after ovulation has actually occurred, meaning there can be little time left to conceive. 
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Research has proved your sense of smell increases when you are ovulating. Science tells us you also look more attractive to your partner when you’re ovulating. 
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Home pregnancy tests work by checking your urine for the hormone hCG, that your body starts to make once a fertilised egg has been implanted in your uterus. However, this process can take several days, so if you take a test straight away, you might want to re-take it nearer to when your period is due. Find out more about when to take a pregnancy test here. 


Thanks to our ovulation calculator sponsor Joie. Click here to view their products.



  • Victoria - 27/09/2015 07:13

    Please help i usually see my periods twice a month what can i do

    • Great - 11/03/2017 16:18

      I saw my period on March 8th and stopped on 11th and I had sex with my partner on the same 11th. Pls am i safe? We are actually using natural family planning.

  • bella - 20/10/2015 10:24

    Pls I noticed dis spotting always instead of my normal mensuration, since I stopped breastfeeding my second baby, wat could be the cause, and can it prevent me from getting pregnant?

  • yourlordac - 27/10/2015 23:10

    I need some help right now. My partner and I had unprotected sex on the 7th, 8th, and 13th October. I usually have period cramps a week before I am due on, but I've had small cramps on one side of my body, which is odd for me. My period arrives around the 27th. I've also been feeling extremely tired. I've taken two pregnancy tests, but they've both said negative. Is it too early?

  • chigold - 30/10/2015 11:39

    tanx for d information

  • Genevieve siame - 04/11/2015 14:32

    Please me n my partner have been try to have a baby for the past 3years now but no avail, we did some txd n we were told everything is fine, pls help us

  • Rinibeth - 10/11/2015 09:34

    Hello please i have been on pregnacare conception and folic acid over four months, I had my period between 3rd October to 6th october then again on 29th October to 1st November. I had sex from 29th October to 4th November. Is it possible I'll get pregnant?

  • Crivers - 03/01/2016 08:59

    Please help. I had my period on the 20 of November. It ended on the 25. Usually I have about 28 to 31 day between my periods. I had sex on the 27 of November, two days after my period ended, but I haven't had sex since. We used protection but I am not on the pill. Please help. What is he chance that I could be pregnant? I am 16 days late for my period and I am freaking out.

    • Mother&Baby - 04/01/2016 17:17

      Hi, the best advice would be to do a pregnancy test, and go to see your doctor.

  • Sokhasl - 07/03/2017 03:09

    I'm trying to conceive more then 4 months after married but there is no shine of having a baby or even more. This is very hopeless for me :(

  • Jade1234 - 21/03/2017 16:57

    Hi, my period in Feb was on the 15th I had sex on the 7th of march. My period came on the 18th or so I thought but was light and only lasted 2 days is there a chance I could be?

  • Ann - 29/03/2017 21:09

    I had an unprotected sex on the 25th and 26th of march and my ovulation starts on the 27th of this month is there a tendency for pregnancy to take place.