Pregnancy calculators are a good way of estimating your baby’s due date, something you’re probably eager to know after you see that positive result on your pregnancy test.

Your estimated due date (or EDD) is there to give you a rough idea of when you can expect to meet your little one. When you see your sonographer for your 12-week scan, also known as the dating scan, you’ll get a more accurate due date to pop into your diary. Read more about what to expect from your pregnancy ultrasound scans.

Our due date calculator helps you estimate your due date by doing the math for you, but you can work out when you’re due yourself if you know the first day of your last menstrual cycle.

A full-term pregnancy normally lasts about 37-42 weeks, 3 weeks from the date of conception. But it can be tricky to pinpoint exactly when you conceived, so most pregnancy calculators use the first day of your last menstrual period to work out your due date instead. That’s why we round up to 40 weeks of pregnancy in total.

So, if you fancy working out your due date yourself, you just need to count 40 weeks from the first day of your last menstrual period. Or, as a shortcut, you can count back 3 months from your last period and then add 7 days. That will give you the day and month of your estimated due date. 

When you take a pregnancy test and find out you’re pregnant you should get an appointment with your GP or local midwife service as soon as you can, around 6-7 weeks. This is known as your booking appointment, and you can read more about this here. At this appointment, your midwife will give you lots of useful information about looking after yourself and your baby during your pregnancy, and what you can expect along the way.

If you feel ready, you might want to tell close friends and family that you’re pregnant right away. Some women, however, choose to wait until after their 12-week scan to announce their pregnancy to the rest of the world, but you should do what feels right to you. If you're not sure, you can speak to your midwife.

Finding out you’re pregnant can bring up a whole mix of emotions, especially if this is your first baby. It’s normal to feel happy, excited, nervous, scared, or all of the above. In our experience, it can help to know what to expect at each stage of your pregnancy. That’s why we have a wealth of information about what to expect every week from now until your due date (and beyond!).

Click here for information, tips and advice on your brand-new parenting adventure. You’ve got this.

Your estimated due date gives you a good idea of when your baby’s due, but it’s not set in stone. When your midwife (Sonographer) does your 12-week scan and measures your baby they might give you a different date. That one will be more accurate, so that’s the one you should work towards as you move along your exciting pregnancy journey.

Only 5% of babies are born on their due date¹, so the likelihood is that yours will arrive a little earlier or later than you expect them – babies rarely work to our schedules! It’s a good idea to start preparing for going into labour from around 36 weeks, and get your hospital bag packed and ready to go (but remember your little one might decide to stay put until after your due date).

Your date of conception can be tricky to pin down, especially if you’ve been trying to get pregnant and doing the work that comes with that. But you can estimate your date of conception by calculating your due date and counting back 38 weeks. 

Your first ultrasound will happen when you’re between 10 and 14 weeks pregnant. It’s usually called your 12-week scan or dating scan, and in most cases will be the first time that you see your baby. 

Last reviewed: October 2024 
Reviewed by Nutricia’s Medical and Scientific Affairs Team