How To Calculate Your Due Date

How To Calculate Your Due Date

Are you concerned you might be pregnant? If you’re experiencing pregnancy symptoms one of the first things you’ll want to know is how to calculate your due date. Even if you are just generally curious about what your due date could be, it’s a good idea to know.

A person’s due date is the estimated date of when an unborn infant will arrive, and it’s important to have an idea of when that will be for planning purposes. Here’s how to calculate your due date using a pregnancy planner and other methods.

Calculate Your Due Date

Calculate Your Due Date With a Pregnancy App

Some pregnancy apps also offer additional features such as a pregnancy countdown and helpful tips for each week of your pregnancy. Here are a few popular fertility apps for you to consider:


An ultrasound is another way to determine your due date. This is typically done during your first prenatal appointment and uses measurements of the fetus to estimate the due date. What is a fetus? A fetus is an unborn offspring, from the embryo stage (the end of the eighth week after conception, when the major structures have formed) until birth.

Please note, however, that ultrasounds can be off by a few days, so it’s best to use this method in combination with others.

If you think you may be between your 7th or 8th week of conception, please consider scheduling an ultrasound with us.

Calculate Your Due Date By Counting 40 Weeks

The average pregnancy lasts 40 weeks from the first day of your last menstrual period. This method involves counting 40 weeks from the first day of your last period to determine your due date. For example, if your last period started on January 1st, your due date would be October 8th (January 1st + 40 weeks = October 8th).

If you are exploring this method, it may be interesting for you to know what is happening at each stage of fetal development. This development is also known as gestational age, or pregnancy week by week. Learn more about 1st trimester (weeks 1-12), 2nd trimester (weeks 13-27), and 3rd trimester (weeks 28- 40) development stages from Mayo Clinic.

Due Date Calculator

If you’re not sure which method to use or want a more accurate calculation, you can use a due date calculator. These are available online and take into account factors such as the length of your menstrual cycle and the date of conception (if known). Simply enter the required information and the calculator will provide you with an estimated due date.

Here are a few popular due date calculator apps for your consideration:

Other Things to Consider

Keep in mind that your due date is just an estimate and your arrival time could be earlier or later than expected. Only about 5% of babies are born on their due date. Additionally, if you have irregular periods or are unsure of the date of your last period, your due date may be more difficult to determine. In these cases, your healthcare provider may use other methods such as an ultrasound to estimate your due date.


This information is not intended to treat or diagnose a health condition. It is for informational purposes only. If you are in a life-threatening situation or need urgent care, please go to your nearest emergency room immediately.

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