Pregnancy Due Date Calculator
Find your estimated due date, conception date and trimester dates in seconds
What you’ll get
- Your due dateYour estimated date of delivery
- Conception dateWhen you likely conceived
- Trimester datesStart and end dates for each trimester
- Pregnancy timelineTrack your journey week by week
How is my due date calculated?
We use the first day of your last menstrual period (LMP) and add 280 days (40 weeks) to estimate your due date. This is the most accurate method recommended by healthcare professionals.
Most babies arrive
between 37 and 42 weeks.
Your due date is just an estimate - babies arrive when they’re ready!
Frequently asked questions
How accurate is a due date estimate?
This gives you the same kind of estimate many people receive before their dating scan. It is useful, but it is still an estimate. Only a small number of babies arrive on their exact due date.
Most pregnancies last somewhere between 38 and 42 weeks, which is why many parents say it feels more like a due month than a due date.
- Pre-term: before 37 weeks
- Early term: 37 weeks to 38 weeks and 6 days
- Full term: 39 weeks to 40 weeks and 6 days
- Late term: the 41st week
- Post term: after 42 weeks
Will my due date change after a dating scan?
It can. A scan between around 10 and 14 weeks may give your midwife or doctor a more accurate due date based on your baby’s development, including the crown-rump length measured on the scan.
Your due date can also be adjusted later in pregnancy if there are medical reasons or if your baby appears to be developing ahead of or behind the earlier estimate.
What are trimesters?
A trimester literally means ‘three months’, so pregnancy is usually divided into three stages:
- First trimester - Weeks 1 to 13
- Second trimester - Weeks 14 to 26
- Third trimester - Weeks 27 to 40+
If you want to follow your pregnancy in more detail, visit our pregnancy week by week guide to see what is happening each week.
Can I plan my due date?
Not once you are already pregnant. If you are overdue, there are things some people try to encourage labour, but there is no guaranteed way to choose the day your baby arrives.
If you are trying to conceive or considering IVF, you can aim to time conception more closely by using our ovulation calculator. Even then, conception is never completely predictable.
What if I'm expecting twins?
The basic due date calculation works the same way whether you are expecting one baby or more than one. However, twin pregnancies often deliver earlier, with the average pregnancy lasting around 35 weeks rather than 39 to 40 weeks for a singleton pregnancy.
Once you have a dating scan, your healthcare team will use the scan measurements to give you the best estimate for your due date.