How to work out your baby's due date
Use our due date calculator to estimate when you will get to meet your new arrival
If you’ve just found out you’re pregnant one of the first questions you’ll probably ask is when your little one will arrive. Our pregnancy calculator is a simple tool which helps you work out your approximate due date before you get a more definite answer at your dating scan, which happens when you are around 12 weeks pregnant.
How does the pregnancy due date calculator work?
Working out how many weeks pregnant you are can be a little confusing. Until your dating scan your pregnancy will be counted from the first day of your LMP (last menstrual period), although ovulation will generally occur two weeks after your LMP, which is when you technically become pregnant. In simple terms, your due day is the first day of your last period, plus 40 weeks.
Is the pregnancy calculator accurate?
Only 5% of pregnancies arrive on their due date with the majority born two weeks either side, but having a better idea of the due date is a good way to ensure you have everything in place in time for your new arrival.
What should I do once I know my due date?
Once you’ve used the pregnancy calculator, take a look at the pregnancy week by week section to find out how you and your baby will develop throughout your pregnancy. Chances are if you’ve just discovered you’re pregnant you’ll already be 4 weeks or even 6 weeks pregnant.
Can my due date change after having a scan?
Possibly. Your first pregnancy scan happens between 10 weeks and 14 weeks pregnant. It's called the dating scan, and gives you a more accurate due date, based on the size and development of your baby.
How likely is my baby to be born on my due date?
It’s not uncommon for babies to be born after their due date, in fact, only about 4% of babies are. Most babies are born somewhere between 37 weeks and 41 weeks of pregnancy, and quite often a week either side of their due date.
What happens if I pass my due date?
You may feel a bit fed up if you pass your due date but your midwife or consultant will not offer induction if you’re only a few days passed your due date. The hope is that you will naturally go into labour in the coming few days.
If you get as far as 41 weeks pregnant, induction of labour will be discussed by your midwife or consultant and your options will be explained to you.
What if I reach 42 weeks pregnant?
A prolonged pregnancy is the name for a pregnancy past 42 weeks (294 days). A small percentage of women (5-10%) would reach this stage, but many maternity units policy says they will induce labour before 42 weeks, so in the UK, only about 3% of babies are born after 42 weeks of pregnancy.
Found this helpful? Read more on early pregnancy: