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 Vivi (not verified) on 6 Jul 2019 - 15:17

      I had sex on 4th of June, saw my period on 22nd of june and it's shorter and some spotting , i have not seen any pregnancy symptoms yet, pls could i be pregnant?

    • By pearl Vicky (not verified) on 2 Jul 2019 - 19:39

      I had my menstruation on 20th of June n I stopped on the 24th of June,when will I ovulate

    • By Samanvitha (not verified) on 10 Jul 2019 - 14:33

      I had got my menstruation on last month 26th June and stopped on July 1st so when is my ovulation day and is there any of getting pregnancy and had coitus on 13th day after menstruation I have menstruation of every 35 days

    • By selba (not verified) on 29 Jun 2019 - 14:50

      I had my periods on 17th Jan n also 2nd_5th Feb had sex on 14th Feb my periods stopped is it boy or girl?

    • By ekanem (not verified) on 28 Jun 2019 - 15:33

      I just started my menses on Thursday 27 june 2019.p2019.please I need to know when I will be most I want to work towards getting pregnant.thanks and my ovalation days too

    • By LiynyuMary-Ann (not verified) on 10 Jul 2019 - 18:50

      I really to Know

    • By Elizabeth mensah (not verified) on 27 Jun 2019 - 19:11

      I had my menses on 24/6/19 when should I have sex without getting pregnant

    • By Nwaogu Ifunanya (not verified) on 27 Jun 2019 - 13:34

      I saw my period on 8th may, when will I ovalute

    • By MRS VIVIAN UWAKWE (not verified) on 26 Jun 2019 - 11:04


    • By Mary (not verified) on 4 Jul 2019 - 01:01

      I gt period on 15 which are good day to gt pregnant

    • By Marjorie (not verified) on 6 Jul 2019 - 10:45

      I see my period July 15th hoping to get pregnant due in 7 days for my PMT looks like we are in the same boat

    • By Lerato (not verified) on 24 Jun 2019 - 22:18

      Had my period last month may from 27 till 4 June... Now on Sunday 23 June I had unprotected sex and haven't gotten a chance to take the emergency pill I'm scared because I'm suppose to be getting my period dis week.... What to do

    • By Maria (not verified) on 23 Jun 2019 - 19:59

      I feel as if am pregnant cause I feel nausea, i vomit, tiredness sometimes very angry but I tired to check I get negative, how should I wait to check again?

    • By Xoxo (not verified) on 23 Jun 2019 - 12:43

      Had an unprotected sex and that to after 3-4 months now I'm scared of pregnancy how to get sure that it was a safe day

    • By debby (not verified) on 19 Jun 2019 - 12:11

      my period started this morning 19/06/2019..when is my ovulation and when am I likely to be pregnant if I meet with my partner.

    • By Chioma (not verified) on 19 Jun 2019 - 11:58

      I saw my period on june 13 and stop on 16.since then no sex, when will i hv sex to get my baby boy. Pls i need twins in other to secure my marriage, i hv already 3 girls. Thanks

    • By Janet (not verified) on 6 Aug 2019 - 05:39

      Twins boys

    • By Susan Efona (not verified) on 19 Jun 2019 - 04:57

      I had just finished my period on 30 may and I had sex on, may 31, June 3, and june 10, can i get pregnant ?

    • By Anonymous (not verified) on 23 Jun 2019 - 22:16


    • By Iris (not verified) on 18 Jun 2019 - 07:31

      My period start this june 11,2019,, and its finished this june15,2019..so what day im going to ovulation and my fertile window start? I want to be become,,.pregnant. Please help ask.. Please help me the maximum date were we have sex..

    • By Anonymous (not verified) on 14 Jun 2019 - 13:51

      I had my periods on 3rd to 5th June 2019 I had sex on 12th June can I get pregnant

    • By Elizabeth peter. (not verified) on 10 Jun 2019 - 20:34

      I have miscarriage last year September. But not able to get pregnant again what can I do?since then I have been having irregular period and have done different scan but fine nothing.please I need help

    • By Anonymous (not verified) on 25 Jun 2019 - 17:52

      Hi i am in the exact same boat I had a misscarage on the 4th sep a should been 17 weeks but everything stopped at 9 weeks... I still have not fell pregnant either. Am just taking each day as it comes.

    • By vida gyasua (not verified) on 5 Jun 2019 - 08:35

      i had my menses on 14 may,and had unprotected sex on 31 may,do i have the chance of getting pregnant.

    • By Nikia (not verified) on 30 May 2019 - 23:54

      My last period was on the 28 of April finish the 2 of may....my period is suppose to come bavk the 28 a may but it doesn't... I had unprotected sex on the 18 and 19 and then on the 24 could it possible be that I am pregnant because I miss my may period...and my breast r so tender?????

    • By Val (not verified) on 31 Jul 2019 - 21:39

      Hi. You might be. Did you founf out yet?

    • By faith (not verified) on 29 May 2019 - 23:27

      period started 21, ended 24, had sex 24, to

    • By Anonymouse (not verified) on 16 May 2019 - 20:41

      My last periods was on the 24 April 2019 to 27 April 2019.
      Then i had sex the following days (28-01 May)
      Can i get pregnant?... nd i also had sex yesterday and stil waiting for my periods?

    • By Joy (not verified) on 16 May 2019 - 00:29

      I had sex on the 13 of april unprotected then had started cycle on April 17th then had sex on April 17th as well . I've had symptoms of pregnancy .

    • By gerremech (not verified) on 15 May 2019 - 11:47

      I had unprotected sex on the 13 May then went mensuration on the 4 may to 9 may then the next month do I get pregnant on next month?

    • By Want to know (not verified) on 14 May 2019 - 14:21

      I had my periods on 16 of April it end on 20 of April and I had sex on 22,23,27 and after that I had light bleeding for a few hours on the 29 of April I have a cycle of 28 days can I be pregnant

    • By lilian George (not verified) on 9 May 2019 - 13:29

      I want a twins baby boy

    • By Sebongile (not verified) on 3 May 2019 - 01:29

      I had unprotected sex on the 10 and 11th Feb then went mensuration on the 12 to 16th Feb then the next month I missed my periods so when did I conceive?

    • By Kim (not verified) on 2 May 2019 - 22:33

      Your ovulation app got me pregnant all other apps were days off my actual ovulation I'm due 14th Jan thank you

    • By By anonymous (not verified) on 30 Apr 2019 - 13:59

      I had my period on 16th April and I started having sex from the 4th day till 27th April every day can I get pregnant

    • By Sajitha (not verified) on 30 Apr 2019 - 07:27

      Lmp 7 April last sexual contact in April 26 how can possible to conceive please reply immediately

    • By Jennifer (not verified) on 29 Apr 2019 - 20:09

      My husband doesn’t stay in the country and I had my last period on the 22/3/19and it ended on the 25/03/19. Then he arrived on the 3/4/19 since then we have been having sex for the past two weeks till 19/4/19and now Am yet to see my period which I have missed for 8days and I have done HCG pregnancy test it was negative
      Pls What should I do best

    • By Cynthia (not verified) on 14 May 2019 - 12:26

      Hi...i think you will need to go for a scan.
      Also are you on any FP plan?

    • By Jk (not verified) on 24 Apr 2019 - 14:24

      I got my periods on the 19th and ended on the 21 April 2019 on the 20th I had unprotected sex are there chances that I can get pregnant?

    • By Anonymous (not verified) on 4 Apr 2019 - 15:10

      I had my period on the 21st of March and lasted for 5days and I began having sex with my husband on the 25th March till April 3th have been feeling as to vomit since April 1st and am expecting my period on the 15th April could I already be pregnant and can I go in for a pregnancy test now

    • By Midwife @Tommys on 4 Apr 2019 - 15:12

      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 Debby (not verified) on 31 Mar 2019 - 08:42

      Hi i had my period on the 21/03/09 to 25/03/09.then i had unprotected sex on the 29/03/09 .I haven't taken any contraceptive pills. But is it possible for me to get pregnant? Please reply.

    • By Kimberly S Thompson (not verified) on 31 Mar 2019 - 03:23

      I had miscarriage on march 21st 2019, when would be best to try again?

    • By LIL (not verified) on 24 Apr 2019 - 00:33

      I had my miscarriage on the 22nd of March. I started 2 weeks after my miscarriage. I started trying on the 31st of March I do not want to waste any time.

    • By lisa (not verified) on 27 Mar 2019 - 03:36

      the last time I had sex was 6 months ago and it was unprotected. recently I have missed 2 periods and have had stomach pains that are different than a regular belly ache, it's not possible to be pregnant right?

    • By Anonymous (not verified) on 22 May 2019 - 01:45

      Stomach pains are not a symptom of pregnancy. Missed period, tender breasts, and nausea with or without vomiting are symptoms of pregnancy

    • By Suma (not verified) on 26 Mar 2019 - 07:14

      I had sex on the day of period it's on 8 and in the mrng i had sex and after noon I got period and ithe bledding was less after doing sex

    • By asha (not verified) on 23 Mar 2019 - 07:47

      my period date after 29th day only one sex i am conceive or not

    • By Nessa (not verified) on 22 Mar 2019 - 03:57

      Hi, I stopped my pills a few days into my second pack. I know I ovulated during that time frame. Well at least all my ovulation symptoms were there. How would I calculate my due date since technically my ovulation was unexpected.

    • By Cynthia (not verified) on 21 Mar 2019 - 15:18

      Pls ma I saw my period on 17feb I haven't I heard unprotected sex throughout pls am I pregnant

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