BabyCenter's Due Date Calculator
If you're newly pregnant and wondering when your baby will be born, you can easily find out your baby's due date with our due date calculator. Just fill in either:
- the date of the first day of your last period
- the date you conceived (if you know it)
- the timing of your IVF transfer, or
- your first ultrasound date
The Due Date Calculator will do the rest!
Our advanced due date calculator will also show your pregnancy timeline, from how many weeks pregnant you are, to when your prenatal appointments may happen, and even when you can expect to feel your baby move for the first time.
How to calculate a pregnancy due date
If you know when you conceived your baby – say, if you were using an ovulation predictor kit or tracking your ovulation symptoms – you can count 38 weeks from that day to find your due date. (Human gestation takes about 38 weeks.) Just choose that calculation method from the pulldown above and put in your date.
But it's hard to know when conception happens for sure because, even if you only had sex once during your fertile period, fertilisation might not happen immediately.
Sperm can live for up to five days inside your fallopian tubes waiting to meet your egg when ovulation happens. So it could be up to five days after you have sex that sperm meets egg and you conceive your baby.
That's why the most common way of finding out your due date is not by using the date of conception, but by one of the following:
First day of your last period
If your menstrual cycle is fairly regular, using your period to find out how pregnant you are can be quite reliable. Also, women are more likely to know when their last period started than the day they ovulated.
In fact, this is the most common way to calculate your pregnancy due date. All you need to do is count 40 weeks from the first day of your last menstrual period (LMP).
Generally speaking, women typically ovulate about two weeks after their menstrual cycle starts. So counting from the first day of your cycle, till your due date, it's 40 weeks (38 weeks of gestation + 2 weeks from the start of your cycle).
If you know the first day of your last menstrual period, you can use our Due Date Calculator to predict your estimated due date.
IVF transfer date
If you conceived through IVF, you can calculate your due date using your IVF transfer date. If you had a Day 5 embryo transfer, count 261 days from your transfer date. If you had a Day 3 embryo transfer, count 263 days. Or select "IVF" from our Due Date Calculator method choices.
Ultrasound scan
If you had an early, first trimester ultrasound scan, the results of the scan can help you know when your baby is expected to be born.
The scan report will give your baby an age in weeks and days. Choose "ultrasound" from our Due Date Calculator dropdown menu. Enter the date of your scan and the age the scan gave your baby, and our calculator will throw up your pregnancy timeline and your due date.
Can my due date change?
During your first trimester, if a scan shows that your baby is bigger or smaller than expected, your doctor might revise your due date. Your doctor will use the age of your baby given in the scan report to calculate your due date.
This is more likely to happen if you have an irregular menstrual cycle length that makes it hard to pinpoint the date of conception.
What if I already know my due date?
If you already know your due date, you can use this pregnancy calculator to see your pregnancy timeline. It will tell you when you'll get to various milestones, and when you may be due for prenatal tests and antenatal appointments.
You'll also find out what your baby's sign and birthstone will probably be and a few famous people who were born on your due date.
Will my baby be born on my due date?
A due date calculation is always an estimate. Only 1 in 20 women delivers on her exact due date. However, you can expect to go into labor any day during the two weeks before or after.
Want more information about how the weeks, months, and trimesters of pregnancy are counted? See our pregnancy timing chartOpens a new window.
