Due Date Calculator – Pregnancy Weeks Calculator

First day of your last period:

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Our due date pregnancy calculator is a service that calculates expected due date and current week/day of pregnancy. Just select the first day of your last menstrual period and check out what to expect!


Which Trimester How Many Months How Many Weeks
2 5, 6, 7, 8
3 9, 10, 11, 12, 13
5 18, 19, 20, 21
6 22, 23, 24, 25, 26
8 31, 32, 33, 34, 35
9 36, 37, 38, 39, 40,41,42


If you suspect that you got pregnant before or after the beginning of menstruation, you can calculate due date after an ultrasound. The new due date will be the most accurate because it’ll be figured out according to medical data. This pregnancy calculator is online aid that makes it possible for you to find answers to a lot of questions.

Here are the main advantages of using our pregnancy calculator:

  • When the woman learns about her new condition she has plenty of questions. She wants to know when she starts showing her pregnancy, when she needs to do ultrasounds, when the baby is going to be born, when she feels the first movements of the unborn child, etc. Due to our pregnancy calculator, it’s possible for a future mother to find out the answers.
  • The due date calculator determines the exact periods of pregnancy trimesters and such significant dates as the day of birth, the conception date, the day of maternity leave.
  • The future mom will learn which pregnancy symptoms she should pay attention to and what to ask her doctor about.
  • The due date calculator will inform the woman about the medical tests she needs to pass and the dates of ultrasounds. It’s a kind of a reminder that is always available.

What are other methods of calculating due date?

  • An ultrasound in the first trimester
  • Naegele’s rule (by the date of your last period)
  • Pelvic exam (determination of the size of the uterus)
  • hCG level assessment
  • First fetal movements

Every doctor determines gestational age by one primary factor (an ultrasound) and two secondary ones (date of the last menstrual period and pelvic exam).

When your due date can’t be estimated by the date of your last period?

  • Irregular menstrual cycle. If your cycle lasts longer than 35 days, the ovulation doesn’t happen on the 14th That’s why, in this case, Naegele’s rule won’t show a correct result.
  • Contraceptive pills. If you’ve forgotten to take a pill on schedule and got pregnant as a result, it means that your ovulation has happened all of a sudden. Its date won’t fit the rule.
  • The risk of a miscarriage during early pregnancy terms. Sometimes such a risk arises when you are in the earliest pregnancy stages. Its main symptom – light bleeding during pregnancy, matching the dates of usual menstruations. So, you can confuse bleeding during the 5th week of pregnancy with your normal period and won’t even know you are pregnant. In such cases, the pregnancy term is detected with the help of an ultrasound.due date calculator

Why do doctors calculate the exact pregnancy term?

  • In order to evaluate how fast the fetus is developing;
  • To find out the expected date of delivery;
  • In order to do a screening and find possible chromosomal abnormalities (Down syndrome and so on);
  • To assess the viability of the baby in the case of premature birth.

For the future mother, the main purpose of detecting gestational age lies in preparations for giving birth and learning every piece of information about prenatal development week by week.

The average pregnancy lasts 40 weeks, though this figure is approximate. The baby can be born from the 38th to 42nd week of pregnancy, this period of time is perfectly safe for the delivery.

Pregnancy is a very important and sometimes anxious time. The childbearing process is a period of discoveries and new curious sensations, especially for women expecting their first child. The new life developing inside of your womb causes unprecedented interest to your own body. The tiny being you love so much already is growing and changing with every passing second, and you, being a future mom, want to know everything about what’s happening inside of you. Due to the fact that the fetus and your own body are constantly changing, the need for knowledge increases even more.  And here it’s important to have some kind of a guidebook meeting your individual needs during each of the pregnancy stages.

Due date calendar week by week will be of particular use in such a situation. It’ll provide you with the information about the supposed condition of a future mom and stage of the development the baby is on at the moment. The expectant mother will take a better care of herself, having learned what her body needs the most at this time.  Besides, she’ll have an idea what’s happening to the baby during each week, which internal organs are formed inside of the tiny body.

Let’s calculate due date with the help of our pregnancy calendar!

Having mentioned all the functions above, we should admit that pregnancy calculator week by week is able to determine the estimated date of birth. It’s very hard to know the exact date of giving birth because the menstrual cycle of each woman is individual. Besides, fetal development is individual too. But, regardless of this, the future mother can find out the approximate date of this significant event. So, individual pregnancy calendar is a very important thing to have for an expecting woman. In spite of the future mother’s lifestyle, she will always be able to understand which pregnancy stage she is on and, according to this term, make a right decision about her diet, rest, and preparations for childbirth.

You can also use our helpful tips for each week of pregnancy posted on our website. Besides pregnancy calculator, there is information about the specifics of every week in the course of pregnancy, photos of the pregnant bellies, and stages of the baby’s development. We are sure it will be a great read!