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Calculator: Expected Date of Delivery – When Am I Due?

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Can’t wait to welcome your little one into the world? Are you already making plans for childbirth? According to the World Health Organization, knowing your expected date of delivery forms a big part of your written plan of birth. So how and where do you start? First, you need to know when your due date is. By using this calculator, you’ll be able to determine quite easily your most accurate expected date of delivery.
At A Glance
  • According To Naegele’s rule: to calculate your due date, simply add 40 weeks (280 days) to the 1st day of your last menstrual period.
  • All due dates are only an estimate. According to statistics, only 5.54% of births take place precisely on the estimated due date. That means about 95% of children are actually not born on the time they are expected.
  • A normal pregnancy can last anywhere from 38 to 42 weeks. It is also considered normal if a woman gives birth 3 weeks prior or 2 weeks after the calculated date of delivery.
  • Other ways of determining your due date include (1) doing an ultrasound, (2) monitoring your week-by-week pregnancy milestones, (3) assessing the size of the uterus, and (4) measuring fundal height.

Your Expected Date of Delivery

All due dates are only an estimate. Calculating your expected date of delivery is not an exact science. According to statistics, only 5.54% of births take place precisely on the estimated due date. This is because every pregnancy is unique. In fact, most are babies are born one week before or one week after the expected date of delivery. That means about 95% of children are actually not born on the time they are expected.

It is normal when a woman gives birth two weeks after the due date of delivery or even 3 weeks prior. This is the case with 90% of all children born in the world. Nine percent of children are known to be born prematurely. Premature birth happens when a child is delivered more than three weeks before the due date. Meanwhile, children who are born two weeks after the calculated date of delivery are born overdue. This constitutes about 1% of the total population of children born.

Due Date Calculator

How to Calculate Your Due Date

Calculating Your Pregnancy According To Naegele’s rule: The Naegele’s rule, named after Dr. Franz Karl Naegele, is one of the standard ways of calculating your due date of pregnancy.

To calculate your due date, simply add 40 weeks (280 days) to the 1st day of your last menstrual period [Source: Stanford Children’s Health]. This is applicable if you have an average 28-day cycle. However, each woman is unique. This is why due dates are only an estimation and not an accurate finding.

Also, remember that your ovulation date and menstrual period are counted as the first two weeks of pregnancy. So if you end up giving birth on your due date, your baby is actually 38 weeks old, not 40.

FAQ: What if I don’t remember the date of my last period?

Answer: This is not uncommon. You can still figure out how to calculate your due date. If you at least know the week of your last menstrual period, your doctor can make an estimate for you. If this is not possible, then your doctor can perform an ultrasound to determine your due date.

Doctor explaining due date to pregnant woman

Other Ways to Determine Your Due Date

If calculating your due date this way does not satisfy you, there are still other ways to determine your date of delivery. Consult with your healthcare practitioner with these methods.

  • Do an early ultrasound. Doing this can predict the date of your pregnancy more accurately. However, even though some practitioners perform them early, they are only for valid reasons. For example, they only recommend doing this if you have irregular menstrual periods, you are 35 years old or older, or if you have a history of difficult pregnancies or miscarriages.
  • You can determine your due date with your week-by-week pregnancy milestonesSome milestones can help in predicting your EDD. Moments like the first time you hear a fetal heartbeat (weeks 9 – 12) or the first time you feel fetal movement (weeks 16 – 22) can give you an idea about your expected date of delivery.
  • Size of your Uterus. Your doctor can likely estimate your EDD by the size of your uterus during your initial internal pregnancy exam.
  • Fundal Height. During each prenatal visit, your doctor measures the top of your uterus. When the fundus reaches your navel, this would mark week 20 of your pregnancy which can be used to estimate your due date.
FAQ: Can my due date change?

Yes. It’s not uncommon for your doctor to you change your EDD. This can happen due to a number of reasons but is no cause to worry. This may only happen if you have irregular periods, your fundal height is abnormal or your first ultrasound dating was off.

When to Start Seeing a Doctor

A lot of soon-to-parents still wonder about the best time to start visiting a doctor. Actually, you should start seeing one the moment you find out that you are pregnant, which is usually after taking a pregnancy test. Prenatal care is important in ensuring a safe and healthy pregnancy. The benefits of good prenatal care are endless. Aside from providing you and your baby the attention you deserve, certain complications or risks can be avoided to help you carry full term. So go ahead and book your first prenatal check-up ASAP!

During each prenatal check-up, the doctor will examine the size of your uterus and monitor your little one’s health and development during the course of your pregnancy. You will also experience certain pregnancy milestones during these visits. Hearing your baby’s heartbeat and seeing him for the first time during the ultrasound are only a few things that will happen. Keep in mind that due to certain factors, it is completely normal if, along the way, there is an adjustment with your due date.


The excitement of meeting your baby for the first time is a feeling many parents around the world have. This is why everyone wants to know when to expect the date of delivery. Additionally, it is very useful so that you can begin planning your childbirth method and everything that relates to it. It’s also an essential information used during prenatal care. Remember, this is only the beginning. Now that you know how to calculate your due date, your excitement finally has a direction, and it is to mark your calendars!

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