pregnancy calculator

So, you’re pregnant! There’s a lot to think about, but first things first: Find out your due date with our pregnancy calculator!

To date a pregnancy, doctors count 40 weeks from the start of your last period (that is 38 weeks since the last time you ovulated, when the fertilisation of the egg took place). Besides, during your first trimester of pregnancy, specifically between 8 weeks pregnant and 12 weeks pregnant, you will have your first ultrasound or dating scan, where the doctor will be able to determine exactly your baby due date. In other words, there’s no better pregnancy due date calculator than the ultrasound!

In the meantime, you can use CaptainMums’ pregnancy calculator, a very easy to use tool that will tell your when your due date is before your doctor does. It will not be as reliable as the dating scan, but it is pretty effective and accurate if you have a regular menstrual cycle.


How to use the pregnancy calculator

Using CaptainMum’s pregnancy due date calculator is the simplest thing! You just need to introduce the date of the first day of your last period and the date you conceived, following your calculations. As a future mummy, you’ve sure been monitoring your ovulation for a while now!

And how reliable is it? Well, the pregnancy calculator will give you your estimated due date (EDD), which is pretty accurate, but that doesn’t mean your baby will be born exactly then. Babies can be born any time between 38 weeks pregnant and 42 weeks pregnant, so, in fact, only 5% of babies are born in their EDD


Can I use the pregnancy calculator if I have irregular periods?

If you have irregular periods, you may have to actually go to the doctor to find out when your due date is. There are other ways other than the pregnancy calculator to find out when your EDD is, or that will keep giving you information to confirm it as your pregnancy advances. Let’s take a look at them:

  • The size of your uterus, which can be measured by the doctor with an examination, can give you clues of how far along you are in your pregnancy.

  • Your fundal height, that is the point where the top of your uterus arrives as the pregnancy progresses and your baby bump grows. Typically, the top is reached when you’re 20 weeks pregnant.

  • Other pregnancy milestones related to the foetus’ progresses, like the first time you can hear his heartbeat (from 9 weeks pregnant to 12 weeks pregnant) or the first time he moves (from 16 weeks pregnant to 22 weeks pregnant)

All these can be considered together to determine if the EDD established is accurate or not (you can also check if it matches what the pregnancy calculator told you in the first place). Some doctors can also choose to perform an early ultrasound before week 8 of pregnancy, since it’s easier to determine how far along you are in the first few weeks. Some doctors decide to perform them in women with irregular periods. 


Pregnancy is a very exciting part of any woman’s life, so trying out CaptainMum’s pregnancy calculator can be even a bit fun! It will only take you a minute and can help you speed up your planning before your first antenatal appointment - so what are you waiting for?