Find out your due date with our calculator

Just found out you're pregnant? Work out when your baby's due with our due date calculator.

📅 Calculate your due date

Tommy’s funds pregnancy research that saves babies’ lives and we’d love to keep you posted with our research news, campaign activities, fundraising events and appeals. Your details will only be used by Tommy’s – we will never give your information to other organisations to use for their own purposes. Read our full data protection and privacy policy for further information. You are free to change your mind at any time.

If your cycle is shorter or longer than 28 days, please adjust the number above.

babycalc-test

How to use the pregnancy calculator

To find your due date you just need to select the date of the first day of your last period on our pregnancy calculator tool and click 'submit.'

You will then receive your estimated due date and the option to sign-up to our pregnancy email. This weekly email gives you fun pregnancy facts, useful tips and great recipe ideas to help you and your baby have the healthiest possible pregnancy.

Are you in early pregnancy? Find out all you need to know about week 4 onwards here.

How accurate is the due date?

The pregnancy calculator gives you an approximate due date, which it works out your due date by adding 280 days (40 weeks) to the first day of your last menstrual period (assuming a 28 day cycle, it is adjusted for longer or shorter cycles). Your period and ovulation are counted as the first two weeks of pregnancy. If you have the baby on your due date, your baby has been growing for 38 weeks, not 40, but you are still classed as 40 weeks pregnant. 

Will I get a more accurate due date later in the pregnancy?

You will have your first appointment with the midwife, the 'booking appointment', between 8 weeks and 12 weeks pregnant. Here you will be given a scan and receive an accurate date for your baby's birth. But if you're impatient to know when your baby will arrive, then our calculator tool gives you an estimate due date without the wait.

Read more

Pregnancy in the news

    Last reviewed on April 1st, 2014. Next review date April 1st, 2017.

    Was this information useful?

    Yes No

    Comments

    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 2 Sep 2016 - 10:41

      Is it normal for ankles to swell early in pregnancy. I am 40, work full time and active.

    • By Midwife @Tommys on 8 Sep 2016 - 09:55

      Hi, some ankle swelling can be normal especially when the weather is warm and you have been active during the day. Try to keep well hydrated and take some time to rest, elevating your legs. If you sit for large parts of the day for work then try flexing your feet up and down regularly and stretching out your legs. If one leg is more swollen than the other then see your GP for a review. If the swelling continues it is worth seeing your midwife for an antenatal check for BP and urine review, though this is more applicable if you are in your second or third trimester. If you would like further advice please call on 0800 0147 800

    • By Midwife @Tommys on 10 Aug 2016 - 14:40

      It is not possible to ascertain if you in early or late pregnancy from the information provided, however I will presume you are in the first trimester. It is not uncommon to have some spotting in the first trimester and some of the harmless causes are an implantation bleed (as the fetal sac settles into the womb) and on intercourse when a cervical erosion may have been the cause . If the bleeding persists and you start to develop abdominal pain, it may unfortunately mean you are miscarrying, with most miscarriages occurring within the first 12 weeks of pregnancy. If this occurs you should seek medical help. If you are concerned please contact one of our Midwives on the pregnancy helpline on 0800 0147 800. We are here from Monday to Friday from 9am till 5pm & happy to have a chat with you to help alleviate your concerns

    • By Anonymous (not verified) on 10 Aug 2016 - 07:52

      I had a little blood lst normal pls. Thanks

    • Pages

    Add new comment