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Mother and Baby

Pregnancy Due Date Calculator

Trying to work out when your baby is due? If you’re having trouble remembering dates and counting up the days on your fingers and toes, don’t worry – use our pregnancy due date calculator to work out your baby's due date.

Simply use the drop-down menus below and click ‘calculate’. 

We need some information

What was the date of the first day of your last period?

Some women's cycles are not exactly 28 days. If your cycle is shorter or longer than 28 days, please adjust the number below.

To work out the length of your menstrual cycle, count from the day your period normally starts to the day before your next period. The average cycle is 28 days.

REMEMBER: This date is just an estimate; only about 4% of babies are born on their due date. Although this tool can give you a rough guide of when to expect your baby, we know all too well that baby will arrive when he is good and ready.

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How likely is it my baby will be born on their due date? 

As we mentioned above, only 4% of babies are born on their due date. Your due date is calculated from the end of your last period, plus 40 weeks or 280 days. That said, it is very likely your baby will arrive a couple of weeks either side of your due date, so it's a good idea to keep this date in mind and get prepared! 

What is a dating scan? 

At your dating scan, otherwise known as your 12 week scan, your midwife will be able to give you a more accurate guide to your due date. You will normally have a dating scan between 10-14 weeks pregnant. During the scan, the sonographer will look at how developed your baby is and measure the length of your baby from his head to his bottom, which helps them to give you an EDD (estimated due date) based on how far along in your pregnancy you are. They will also check you are only expecting one baby not two, and that your baby is developing in the right place.

How do I work out how pregnant I am? 

Pregnancy normally lasts from 37 to 42 weeks. It can be tricky at first to work out how to count your pregnancy in weeks and months, as when we measure your pregnancy from the start of your last period, your baby is actually two weeks younger than the pregnancy start date, otherwise referred to as the 'gestational age'. So, this means when your doctor tells you you're four weeks pregnant, your baby's gestational age is actually two weeks. 

How do I know what trimester I am in? 

Trimester means 'three months', so your pregnancy will be divided into three trimesters. Your first trimester will be from conception to thirteen weeks and six days. Your second trimester is from 14 weeks to 27 weeks and six days. Your third trimester is from 28 weeks to when you give birth. 

How big is my baby at each stage of pregnancy? 

Although all babies grow at different rates, you can work out how big your baby is in terms of the fruit and veg you might recognise in the supermarket here. 

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  • Gabriella - 10/03/2016 17:16

    This site has really helped me alot.

    • laura1 - 18/08/2017 20:03

      I wass wondering if there is someone that could help me out . I took a pregnancy test last week and it was negative .and took one yesterday and today and it was positive . My last period was 11th of july . Would it be possible to tell me when i concieved please

  • Caroline - 04/02/2018 20:22

    I have a question, when I was 16 weeks I started feeling stomach pains and it was so painful and I whenever am feeling the pain I could diarrhoerate but later it stopped but now am 23 weeks my breasts bring out milk and the stomach pains are back I don't know what to do,please help

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