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.


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


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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 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!?

    • By Midwife @Tommys on 18 Aug 2017 - 12:11


      I would suggest that you take a pregnancy test if you have still not come on your period.
      It is difficult to predict from dates alone as I am unsure of when you ovulated.
      Please free to call the Pregnancy Line on 0800 0147 800 to discuss further.

    • By Anonymous (not verified) on 12 Aug 2017 - 02:12

      My last period was July 20th and lasted about 3 to 4 day i had sex August 7th which is about 11 to 12 days before my next menstrual cycle. My long term boyfriend and i used the pull out method, he pulled out on time every time but im starting to second guess. Should i just wait for my next period To confirm my paranoia ? Or by the way my dates are it is already less likely to have happend

    • By Midwife @Tommys on 14 Aug 2017 - 15:53

      The 'pull out' method is not a reliable method of contraception. however it is too soon to know whether you are pregnant. Can I suggest that you seek advice from your GP or sexual health clinic. They will be able to assess your needs and help you decide on your best options.

    • By Anonymous (not verified) on 10 Aug 2017 - 04:52

      My period start 21st month of july. Ends 25th. Then i have unprotected sex in 26th.. Is it possible to get pregnant?

    • By Midwife @Tommys on 10 Aug 2017 - 12:18

      Hi, Thank you for your comment.

      If you have unprotected sex and you are not on any other form of contraceptive then there is always a chance that you could get pregnant. On average the most fertile time for a women would be around day 14 of her cycle but this can be different for everyone. It would be advisable that you wait and see if you miss your period, if you do then you will need to do a pregnancy test to see if you are pregnant or not. If you are still concerns then you can always contact your GP for further advice. hope this helps, Take Care, Tommy's Midwives x

    • By anonymous (not verified) on 1 Aug 2017 - 14:48

      Had what i thought was my period on 27th july 2017, but very light compared to what they normally are. When should i take a pregnancy test?

    • By Midwife @Tommys on 2 Aug 2017 - 09:29

      Hi, it is worth waiting for a week or so before you do a pregnancy test so that the HCG levels in your urine have time to build up before you do a pregnancy test. Also, the best time to do a pregnancy test is first thing in the morning as the HCG levels have built up overnight and are more prevalent in the first void of urine in the morning.
      Please take good care of yourself

    • By Anonymous (not verified) on 30 Jul 2017 - 02:24

      I can't remember my last date of my period I think July 3-5 I have regular periods. I had unprotected sex on Morning of July 25 what's the possibility I could be pregnant (FYI I wasn't trying) I've had 2 miscarriage, one abortion

    • By Midwife @Tommys on 31 Jul 2017 - 12:47

      If you have had unprotected intercourse there is a possibility that you could become pregnant. You can obtain morning after contraception up to five days after you have sex. Contact your doctor or your pharmacist for advice.

    • By Anonymous (not verified) on 28 Jul 2017 - 11:02

      I expected my period in the 6th of July and I didn't see my period
      Had unprotected sex on the 8th of july
      Till now I haven't seen my period
      Can I be pregnant

    • By Midwife @Tommys on 28 Jul 2017 - 11:09

      If you have been having unprotected sex then there will be a chance that you could be pregnant especially if you are late with your period. I would suggest to do a pregnancy test to see if you are. If this test is negative and your period still does not come then to repeat the test in 5-7 days as it maybe that it is a little early and need time before the test can detect the hormone level. Take care x

    • By Anonymous (not verified) on 24 Jul 2017 - 02:03

      Hi i had my iud out on june 27th had sex same day untill my period on the 2 of july then had sex eveyday from the 7th to the 19th i took a pregnancy test 10 days before my next period but it came out negative just wanted to know if it's to early to know

    • By Midwife @Tommys on 24 Jul 2017 - 14:57

      Hello. If your last period was 2nd July it would be too soon to show up on a pregnancy test. Please remember though that for some women conception is not immediate and it can take several months before a pregnancy occurs. Best of luck

    • By Anonymous (not verified) on 11 Jul 2017 - 12:41

      I have been trying to conceive for almost a year now. I started using the ovulation tests but had to stop as it was disheartening every time I started my menstrual cycle. It made me feel so down to think I was doing the right things at the right time but no positive results. 2 years ago I had an ectopic pregnancy but they managed to save my fallipian tube. A couple of months ago I went to my doctor who did blood tests on two different occasions of my menstual cycle and they said there appeared to b no problems of me ovulating and all was well. I have also been taking Pre-vitamins that was recommended. I have been told to stop trying so hard and the past couple of months Iv tried to not think any more into it all but still no luck. Any suggestions as to what could help me please

    • By Midwife @Tommys on 13 Jul 2017 - 10:39

      Hi thank you for your comment. You are understandably feeling disheartened after nearly a year of trying to conceive but please feel reassured that over 80% of couples will get pregnant after 1-2 years of trying. This can be effected with age but you are doing everything right by taking your vitamins and being as healthy as you can. If you haven't conceived after a year then you are advised to see your GP who will be able to advice you further. It is easier said then done but try and relax as much as you can, take your time and hopefully this will help with conception. If you would like any further advice them please contact [email protected] or call us on 0800 0147 800 Monday to Friday 9am-5pm. Take care, Tommy's Midwives x

    • By Anonymous (not verified) on 3 Jul 2017 - 12:58

      I have 4 kids one abortion one lost in march this year I had 1 c section 3 normal deliveries I normal get pregnant easy fast ive been check over by doctors everythings looking good but I am tried ive trying nearly every night and only getting negatives test am getting tried and as a women and mum already I don't want nothing more I am 28 so thought It could be my age am not sure need advise ??????? help

    • By Midwife @Tommys on 3 Jul 2017 - 16:03

      The best advice is to look carefully at your lifestyle and ensure that you are in the best health possible. Ensure your weight is within the normal range and that you are exercising regularly. Remember to stop smoking and alcohol and to start taking folic acid and vitamin D.

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