Ovulation calculator

Each woman's menstrual cycle is different, so getting to know your body better can improve your chances of conception.

This ovulation calculator allows you to find out when you'll be most fertile, and what your due date would be if you got pregnant on these dates.

Ovulation calculator

What was the first day of your last period?

What is your average cycle length?

Are you ready to conceive? Take our quick quiz to find out.

For the best chance of getting pregnant, you need to maximise the chance of your fertile egg and your partner's sperm getting together. You can only get pregnant on the few days each cycle around ovulation, when an egg is released.

When is the best time to conceive?

To increase your chances of getting pregnant, you need to get your fertile eggs and your partner's sperm together as often as possible. You can only get pregnant on the few days each cycle around ovulation, when an egg is released.

How does the menstrual cycle work?

  • Your cycle starts on the first day of your period and continues up to the first day of your next period.
  • At the same time, eggs begin to mature in the ovary.
  • The lining of the womb thickens ready for fertilisation.
  • During ovulation your cervical mucus becomes thinner and clearer to help the sperm reach the released egg.
  • About 10 to 16 days before the start of your next period, an egg is released from one of the ovaries (ovulation).
  • If sperm is present at the moment of ovulation, or some time during the next 24 hours, the egg may be fertilised.
  • If the egg has not been fertilised, the egg is re-absorbed by the body, the hormone levels drop, and the womb lining is shed. This is the beginning of your next period.

Read more here about how pregnancy works

Conception and sex

To boost your chances of conceiving, aim to have regular sex throughout your cycle so you know that there should hopefully be good-quality sperm waiting for the time that the egg is released. An active sex life is all most people need to conceive.

If you are quite sure when you ovulate each month you can give yourself the best chance of getting pregnant by having sex in the days leading up to ovulation. Continue having sex during ovulation. After this your fertile time will be over for that cycle.

Taking a pregnancy test? Read about how pregnancy tests work.

How to spot the signs of ovulation

Ovulation usually happens about 10 to 16 days before the start of your next period, so  it helps to know your cycle length before you start trying to conceive.

You may never have considered when you might ovulate within your cycle, and if you have been using a hormone contraceptive such as the Pill, you won’t have had a natural menstrual cycle for a while.

As a first step, mark on your ovulation calendar the dates that you bleed during a period. You can then count how many days from the first day of your period to your next period to work out the length of your cycle.

Cervical mucus changes

The cervix secretes mucus throughout the menstrual cycle, starting off sticky white and gradually becoming thinner and clearer.

Before and during ovulation the mucus increases and becomes much thinner, slippery and stretchy. Women often compare it to raw egg white.

This thinner mucus is designed to help the sperm swim easily through it. It indicates that you are in your fertile phase, so this is the time to have sex if you want to get pregnant, but use contraception if you do not!

The last day you notice the wetter secretions is sometimes known as ‘peak day’ and for most women this occurs very close to the time of ovulation.


You can also find out about your menstrual cycle by keeping a note of your temperature each morning when you wake up. Your temperature rises by about 0.2°C when ovulation has taken place.

As it is only an indicator that you have ovulated, and doesn’t tell you when your fertile time starts, this is not very useful for most women.

Using ovulation test kits (also known as ovulation predictor kits)

Ovulation predictor kits are available from chemists and are fairly simple to use. They work by detecting a hormone in your urine that increases when ovulation is about to take place.

The simplest ovulation test kits check for luteinising hormone (LH), which surges 24-36 hours before ovulation. This will help to identify the best two days for conception, although a woman can be fertile for a day or so before and after this time.

It is best to become familiar with your usual menstrual cycle to help figure out when you should start testing. If you have an irregular cycle then an ovulation predictor kit can help you identify the time of ovulation, but expect to use more of the test strips.


  1. Macdonald S, Macgill-Cuerden J (2012) Mayes’ midwifery: a textbook for midwives, 14th edition, London Balliere Tindall


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    Last reviewed on June 13th, 2017. Next review date June 13th, 2020.

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    Please note that these comments are monitored but not answered by Tommy’s. Please call your GP or maternity unit if you have concerns about your health or your baby’s health.
    • By Anonymous (not verified) on 3 Oct 2017 - 02:02

      Hi there,
      My husband and I decided we wanted to start TTC. I finished my last pack of Bc pills on 9/12 and had my period on 9/15-9/19. I have been taking ovulation tests everyday a week since my last period. All the tests have come up negative. When can I expect a positive ovulation test?

    • By Midwife @Tommys on 3 Oct 2017 - 10:31

      thanks for your post. I think as you have been on the pill it would be good to get an idea of your natural cycle length first by noting on a calendar how many days your period lasts for and how long until your next period begins. Ovulation usually occurs 10-16 days before your next period so having regular sex throughout your cycle when TTC is advised. In the link below there are other signs to show that you are ovulating so that you don't need to use up all your ovulation tests.
      It is also good to remember that 80% of couples get pregnant within a year and 90% within 2 years.
      Good luck!
      Anna-Tommy's Midwives

    • By Anonymous (not verified) on 1 Oct 2017 - 08:45

      My last menstruation was on the 15th to 17th of September 2017. I have been having unprotected sex since then, I did my pregnancy test (blood) on the 29th of September, it was negative. Can I still get pregnant with this few days to my messes?

    • By Midwife @Tommys on 2 Oct 2017 - 12:15

      The earliest that you can expect a positive pregnancy test would be mid October. You would expect to ovulate about 2 weeks after your period and it would take another 2 weeks before a positive pregnancy test is possible.
      Take care x

    • By felicity (not verified) on 28 Sep 2017 - 18:48

      i saw a blood shed on 4th of september and stoped flow on the 9th and 10th of september, i saw a white raw egg on the 19th and 21st of september.i had sex on the 21st of september.it is possible to have been pregenant with a baby boy.

    • By Midwife @Tommys on 29 Sep 2017 - 12:08

      It is very difficult to know whether a spontaneous pregnancy will result in a baby boy or girl. Therefore I am unable to say. You will however find out the sex of your baby around 20 weeks at your scan.

    • By Anonymous (not verified) on 27 Sep 2017 - 10:16


      I recently (28th August 2017) underwent a D&C operation for a missed miscarriage. Our baby Robin measured 8 weeks when we should have been 12+1. Yesterday I started my first menstrual cycle and we were advised to try again after my first cycle. Is there anything I can do to help lower my chances of another miscarriage this time around. This was my second miscarriage. I had one many many years ago but never had any medical intervention as I was young and afraid. My husband and I desperately wanted a baby and after lots of in-depth conversations we wish to fall pregnant asap again.

    • By Midwife @Tommys on 27 Sep 2017 - 12:29

      Hi Thank you for your comment.

      We are sorry to hear about your losses it can be a very difficult time for you and your husband and it is understandable that you want to start to try again now that you feel ready too. The best things that you can do is to keep taking pregnancy vitamins, eat a healthy diet and if you smoke or drink alcohol then try and reduce this as much as you can or the ideal would be to stop altogether. Doing these things will give a pregnancy the best start possible. Try and get enough rest and be kind to yourself as well. Hope this helps, if you need any further advice please contact the Tommy's Midwives on 0800 0147 800 9am-5pm Monday to Friday or email [email protected] Take care, Tommy's Midwives x

    • By Ammu (not verified) on 26 Sep 2017 - 14:16

      My last period of first day is Sep 1st and end was on Sep 5th. I got spotting once on Sep 15th and had a unprotected sex on Sep 17th.
      9/25 - I had uterus and abdominal pain and also backpain,felt nauseous and little dizzy. Today(9/26), having severe lower back pain.
      IS there any changes are there to get pregnent?

      My last period:
      June: started on last week - ends on July 1st
      Aug: started and ended in 1st week
      Sep: started Sep 1st - ended on Sep 5th

    • By Midwife @Tommys on 26 Sep 2017 - 14:34

      Hi Ammu.
      It would probably be sensible to do a pregnancy test if you have had unprotected sex- you may need wait another week or so for the test to accurately show if there is a pregnancy there or not. Abdominal pain, nausea, dizzyness can be a sign of pregnancy, but this can also be attributed to many other things too. So it is hard to know without doing a test. Take good care of yourself! All the best!

    • By Anonymous (not verified) on 25 Sep 2017 - 10:32

      My last period start date was 30th Aug I had unprotected sex on 19th September could I be pregnant? My cycle is normally 32/33 days. Please help?

    • By Midwife @Tommys on 25 Sep 2017 - 11:12

      Yes there is a chance that you are pregnant if you have had unprotected sex, but it is not possible to confirm until you are able to do a pregnancy test at around the time your period is due.

    • By Anonymous (not verified) on 23 Sep 2017 - 16:48

      I had my menses on the 29th of August and had unprotected sex on the 8,9,11,and 13th even on the 13 I felt abdominal pain because I was ovulating but Im feeling pain as if I'm about to mensutrate which will be on 30th August .does that mean I wasn't able to get pregnant?

    • By Midwife @Tommys on 25 Sep 2017 - 11:08

      No it is not possible to say whether you are pregnant or not until your period is due. Remember though that getting pregnant can take time and there is no reason to worry if it takes more than one cycle to conceive. Check out this page https://www.tommys.org/pregnancy-information/getting-pregnant

    • By Anonymous (not verified) on 20 Sep 2017 - 22:11

      I came on my period aug 27th or aug 28th got off period aug 30th i usually last for t days bit this period was short like 3-4 days long i had sex sept 17 and sept 18th could i be pregnant becuase the interent keeps giving me yeses and no's

    • By Midwife @Tommys on 21 Sep 2017 - 13:35

      Hi Thank you for your comment.
      If you have been having unprotected sex during your cycle then there is every chance that you may become pregnant. It is too early to say at this time so it would be advisable for you to wait until your period is due, if you miss your period then you can do a pregnancy test. Testing first thing in the morning is the recommended time. The internet will only tell you when your most fertile time is to try and conceive, it wont confirm that you are pregnant, you will need to do a pregnancy test for a reliable result. Hope this helps, Take Care, Tommy's Midwives x

    • By Anonymous (not verified) on 20 Sep 2017 - 03:53


      My last Pd started on 8/3/17 normally it always starts on the 6th of every month so I was a few days early. I ended up bleeding for 3 weeks and was told to double up on bc pills to stop the bleeding. I stopped around the 20th of August and discontinued the pills. It's now 9/19 and still no Pd. Do you think it's possible to be pregnant? Thanks.

    • By Midwife @Tommys on 20 Sep 2017 - 10:19

      Hi there. It is really very difficult to know. The most sensible thing to do in this situation is to take a pregnancy test, either at home or at your GP surgery. If your GP is concerned about the constant bleeding (with or without the presence of a pregnancy) and erratic cycles for you, then you should be referred to a gynecological specialist for review. There is no need to panic, but i think it would be sensible to know your pregnancy status, and move on from there with your GP and/or gynecologist. Please do feel free to contact us again if we can be of any further assistance. Take care :)

    • By Worried (not verified) on 15 Sep 2017 - 20:38

      I got my cycle June 1st, it lasted about 6 days, they are usually every 30 to 31 days. I had Protected sex on June 8 th and unprotected sex on the 13th and 19th but we used the pull out method. I implanted on June 27th. I found out I was pregnant and the baby is due in march. How can I figure out which date I actually got pregnant?

    • By Midwife @Tommys on 18 Sep 2017 - 10:37

      Hi - Thank you for your comment.
      If your periods are regular within a 30-31 day cycle, then according to your dates of the first day of the last menstrual period of 01/06 - it is more likely that your baby was conceived somewhere between 13-20th June.

    • By lola (not verified) on 2 Dec 2017 - 16:26

      I had my period on 18th of nov to 22 of nov I started having unprotected sex with my husband from 25,26,28,29 and 2ND of dec is their any chance of pregnancy?

    • By Midwife @Tommys on 5 Dec 2017 - 11:58

      Hi Lola,
      having regular, unprotected sex during your cycle does mean you can become pregnant as sperm can live inside your body for 5-7 days so if you ovulate during this time you could definitely become pregnant. You can either wait for your period or some pregnancy tests will allow you to test 6 days before your period.
      Warmest wishes
      Anna-Tommy's Midwives

    • By Anonymous (not verified) on 13 Sep 2017 - 17:21

      Hi, my last period first day was on 25th August n I had a unprotected sex on 10th September n 12 September can I be pregnant? N wat ll be the best time to test for result.

    • By Midwife @Tommys on 14 Sep 2017 - 13:58

      Hi, Thank you for your comment.
      If you have had unprotected sex and are not using any form of contraception then there is a chance that you can get pregnant. The earliest that you can test is around 5 days before your missed period but this depends on the brand of pregnancy test that you use. you may want to wait and see if you miss your period but you can test early if you want too. Hope this helps, take care, Tommy's Midwives x

    • By Alicia (not verified) on 12 Sep 2017 - 03:19

      I had my last period July 28th had unprotected sex on my cycle and since uo to now. Not sure when best time to take a home test. Should of started again August 28th but didnt.

    • By Midwife @Tommys on 12 Sep 2017 - 11:57

      Hi Alicia,
      as you've had unprotected sex and didn't have a period when expected it would be fine to do a pregnancy test now.
      Get back in contact if you have any questions.
      Anna-Tommy's Midwives

    • By annonymous (not verified) on 11 Sep 2017 - 06:24

      Hi, my periods started on the 3rd till today,i had unprotected sex on the 8th, is it possible that I can fall pregnant?

    • By Midwife @Tommys on 11 Sep 2017 - 12:08

      Hi - if you are having unprotected sex there is always a chance of pregnancy. If you think you maybe pregnant, a pregnancy test taken around the time when your next period is due will help you determine if you are not.

    • By anonymous (not verified) on 10 Sep 2017 - 11:30

      My cycle started on the 24th August and I had unprotected sex on the 8th September and I tried to calculate when I would be fertile. It said I'd be fertile between the 2nd of September & the 8th. How soon can j do a test?

    • By Midwife @Tommys on 11 Sep 2017 - 12:11

      Pregnancy tests work by detecting one of the key early signs of pregnancy: a hormone called human chorionic gonadotrophin (hCG). This hormone is only made when a woman is pregnant.
      Traces of hCG can be found in the urine from three to four days after implantation, but the concentration needs to continue to build up to a level at which the test can detect it and give a positive result. The best time to take a pregnancy test is from the day that the period is missed.

    • By Brenda (not verified) on 9 Sep 2017 - 20:32

      Hi my last period was july 16th 2017 i sould be 8 weeks pregnant today. Sept 9 2017 but o went to the doctor and the doctor explained on sept 7 2017 that the baby is measuring 6 weeks 4 days. Which is 6 weeks 6 days today. How many weeks am i??? On ovulation day the egg is released 12-48 hours on that day or during ovultation days? I was ovulating july 25-july 31 which day did i concieve? Thank you!

    • By Midwife @Tommys on 11 Sep 2017 - 12:31

      Hi - Ovulation usually happens about 10 to 16 days before the start of your next period, however it can vary when you ovulate within your cycle too. If you have an ultrasound and been told your gestation, that is the most reliable estimation of your baby's due date.

    • By Confused (not verified) on 9 Sep 2017 - 05:18

      My period came down July 28 had unprotected sex August 11,15, & 16.Period came down on August 19-23 wasn't heavy. My period should have came down on the 28 it didn't. I'm 42 yrs old.

    • By Midwife @Tommys on 11 Sep 2017 - 12:34

      If you have been having unprotected sex and your period is late it is possible that you are pregnant so the next step would be to do a pregnancy test.

    • By Anonymous (not verified) on 3 Sep 2017 - 00:21

      Last period start not sure but between June 30 and July 2 end on July 9 had sex on July 10 with protection and then 2 more times with no protection didn't got my period on August and on the 14 got a positive pregnancy test when did I got pregnant? And what would be my due date. ? I'm very concern I had a miscarriage back in February and I just got an ultrasound and they said baby is way to small they go by my last period and said I'm 8 weeks but I'm sure I'm not 8 weeks cause I was not with my husband for over a month until the dates above please help

    • By Midwife @Tommys on 4 Sep 2017 - 12:27

      Yes, by your dates you are up to 9 weeks today, but the scan will confirm how far along the pregnancy is based on the size of the foetus.

    • By Anonymous (not verified) on 30 Aug 2017 - 18:06

      Hi there. I had my last normal period on 23July. It was due 23 Aug. Im now 7days late. Which is weird. I had heavy cramping a week ago and now i just feel bloated and iritated. Have been throwing up on random times of the day. Did a preg test on sunday past and was negative... Any advise

    • By Midwife @Tommys on 31 Aug 2017 - 10:06

      Hi, Thank you for your comment.
      It would be advisable for you to do another pregnancy test to see if you do get a positive result. If you have been having unprotected sex and you think you may be pregnant having missed your period ,then you can see your GP. They can perform a blood test to check the level of pregnancy hormone in your blood, this will confirm if you are pregnant or not as it is much more sensitive then a urine pregnancy test. Hope this helps, take care, Tommy's Midwives x

    • By Anonymous (not verified) on 31 Aug 2017 - 11:45

      Thank you... I checked my period calendar and in my ovulation period i had unprotected sex. I will do another preg test and then go see a dr. Cause in the evening im more nauseated than normal. And the bloating urgh. Thanks again. Take care

    • By Midwife @Tommys on 31 Aug 2017 - 11:58

      You are very welcome, if you need any further advice then please contact the Tommy's midwives on [email protected] or call 0800 0147 800 Monday to Friday 9am-5pm. Take care, Tommy's Midwives x

    • By Anonymous (not verified) on 2 Sep 2017 - 19:16

      Hi! I have unprotected sex, 21 days before my period,is it safe? Cause my boyfriend did the pull out method or is it possible that to me to be pregnant?

    • By Midwife @Tommys on 4 Sep 2017 - 16:17

      Hi, If you have unprotected sex there is always a chance that you can become pregnant. The 'pull out method' is unreliable as a method of contraception. If you are not wanting to become pregnant I suggest that you see your GP or contraceptive clinic for advice.

    • By Midwife @Tommys on 29 Aug 2017 - 14:52

      Hi, if you are trying for a baby it is helpful to know how long your cycles are, if they're regular and then you can see when you are most fertile. Have regular sex through your cycle and try to stay relaxed about pregnancy. In fact 80% of couple will get pregnant within the year.
      I hope this helps let us know if you have any other questions
      Best wishes
      Tommy's Midwives

    • By Midwife @Tommys on 29 Aug 2017 - 14:42

      I'm not quite sure what you're asking but if you email a bit more detail I will try to help.
      Best wishes
      Tommy's Midwives

    • By Midwife @Tommys on 29 Aug 2017 - 14:40

      I'm not sure what you are asking. Please get back in contact with more detail and I'll be happy to help.
      Best wishes
      Tommy's Midwives

    • By Anonymous (not verified) on 27 Aug 2017 - 14:16

      Hi I usually have 10 to 12 days of bleeding if I have to plan for a baby when to try

    • By Sophia (not verified) on 26 Aug 2017 - 20:49

      Pls can a water sperm get someone pragnant pls

    • By Anonymous (not verified) on 21 Aug 2017 - 12:09

      hello, i had my menses on the 31/7/2017 finished on the 4th of August and on the 11th through to 14th August i have been having unprotected sex. Could i be pregnant thank you

    • By Midwife @Tommys on 24 Aug 2017 - 14:08

      Hi, Thank you for your comment. There is every chance that you could be pregnant as you have been having unprotected sex. We would advice that you wait to see if you miss your period and then if you do, you can do a pregnancy test, you can also buy pregnancy tests that detect a pregnancy up to 5 days before a missed period if you wanted to test sooner. If you are actively trying from a baby, then you can start to take pregnancy vitamins now before conception. Hope this helps and we wish you lots of luck. Take care Tommy's Midwives x

    • By Tes (not verified) on 18 Aug 2017 - 05:55

      I had my period July 20- July25th, 2017. I had unprotected sex the 8-11th days of my cycle and now I miss the first day of my period today the 17th. Can I be pregnant!?

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