Pregnancy Due Date Calculator

Are you pregnant and sick of Googling, “When is my due date” or “When am I due”?

We’ve got you covered!

In this article, we offer you Pregnancy Due Date Calculator and cover everything you need to know about why due dates are important, other methods for calculating your due date, and how to manage your expectations ahead of giving birth. 

What Is a Pregnancy Due Date? 

A pregnancy ‘due date’ is the date when delivery is estimated to occur – i.e. when the pregnant individual will give birth. 

Due dates can be determined by a doctor or midwife, taking into account menstrual cycle dates, the estimated conception date, and ultrasound scans. In cases of in-vitro fertilization (IVF), the IVF transfer date is also taken into consideration. 

Due dates are important to calculate for pregnancy because they allow healthcare providers to monitor the health and development of the fetus. They also allow families to plan ahead for delivery. 

Calculating Your Pregnancy Due Date 

Last Menstrual Period (LMP)

One of the most basic ways to estimate your pregnancy due date is by taking the date of your last menstrual period and then adding 280 days. This will give you the earliest possible due date at around 40 weeks. 

Most online pregnancy calculators utilize this calculation method. However, it is not necessarily the most accurate way to predict your due date, as it is based on a 28-day cycle and does not take into account the timing of ovulation. 

Conception Date

If you keep track of the dates you have sex and ovulate, you can also calculate your due date based on when you think you conceived. For this method, simply take your estimated conception date and add 266 days (i.e. 38 weeks) to arrive at your earliest due date. 

Similar to the LMP method, you can find several online due date calculators that utilize this method. 

It’s important to note that sperm can live inside the body for up to five days after intercourse – meaning the date you had unprotected sex may not be the same date that you conceived.

Ultrasound Scan

The most accurate way to estimate your pregnancy due date is with a first-trimester ultrasound scan, which is typically given at around 12 weeks. During this scan, the ‘crown-to-rump’ measurement can be taken, which helps the doctor estimate your due date based on the parameters of the fetus.

After the first trimester, it becomes increasingly more difficult to determine gestational age with an ultrasound. If you did not have a first-trimester ultrasound, your doctor will still be able to estimate your due date based on your LMP and other fetal measurements (such as head and abdominal circumference). 

IVF Transfer Date

It is also possible to estimate your due date based on your IVF transfer date. For example, if you had a three-day transfer, take your transfer date and add 263 days to estimate your earliest possible due date. If you had a five-day transfer, add 261 days from your transfer date. 

IVF due date calculators are also fairly easy to find online. Your fertility specialist will also be able to assist with estimating your due date.  

Factors Affecting the Accuracy of Your Estimated Due Date

Estimating your due date is just that – an estimation. Here are a few factors to be aware of that can interfere with the accuracy of your estimated due date. 

• Menstrual Cycle Length. Most LMP due date calculators are based on a 28-day menstrual cycle. However, cycles can last between 21 to 35 days, with ovulation normally occurring as early as day 10 or as late as day 21. This means if ovulation occurs earlier (or later) than average, your due date will also likely be earlier (or later) than the estimated LMP due date. 
• Irregular Periods. If your menstrual cycle varies in length from cycle to cycle, this can also interfere with your ability to accurately estimate your due date – especially if you are unsure of when you ovulate. 
• Ultrasound Timing. During the first trimester, an ultrasound scan can help your doctor estimate the gestational age of the fetus, which in turn helps them estimate your due date. However, ultrasound scans are not as accurate at measuring gestational age during the second and third trimester. 

It’s important to highlight the fact that only approximately 1 in 20 women actually give birth on their due date. Due dates are not an exact science, and it’s okay if you give birth a few days before or after your expected due date. In fact, giving birth anytime between 37 and 42 weeks is considered normal. 

Signs That Indicate Your Due Date Is Near

The final weeks of pregnancy can be both exciting and nerve-racking. After week 31, the baby starts to rapidly gain weight and by week 39, they are considered full-term! 

During this time, you may start to notice some of the very early signs and symptoms that you are approaching labor. The most common symptoms include: 

• Increased vaginal discharge, which may include the passing of the mucus plug
• Lightening – when the fetus drops lower into the pelvis (this is also sometimes referred to as ‘engagement’)
• Regular contractions occurring two to five minutes apart
• Water breaking – when the amniotic sac ruptures, resulting in a release of fluid from the vagina

Your doctor will go over everything you can expect in the weeks leading up to labor. If your water breaks and/or you experience more frequent and painful contractions, it’s time to call your healthcare provider and head to the hospital. 

Managing Expectations Around Your Due Date

Remember – your due date is just a rough estimation. Instead of fixating on your exact due date, try to focus on when you’ll be 37 to 42 weeks pregnant. This will help you manage your own expectations of when you are most likely to give birth. 

It’s only normal for the anticipation of giving birth to be a bit stressful. If you are feeling anxious about the experience of labor or becoming a parent, the following tips can help ease feelings of anxiety ahead of childbirth: 

• Distraction. Keep yourself busy with doctor-approved activities – such as going for a walk, watching TV, meeting a friend for lunch, moving your body with gentle exercise and stretches, reading a book, or getting creative. 
• Routine. Try your best to stick to a daily routine, this will help you stay grounded and (hopefully) sleep better at night. 
• Preparation. You’ll be very busy once your little one arrives! Get prepared ahead of time by packing your hospital bag, setting up the nursery, and stocking up on the essentials for your household. 

If you start to notice early signs of labor, call your doctor or midwife immediately. They can provide guidance on what you should do next. 

Setting Yourself Up for Success With Perinatal Support 

Before Pregnancy

If you are actively TTC (trying to conceive), there are several things you can do to maximize your chances of conception. 

The first thing we always recommend is to familiarize yourself with your hormone health – because if your reproductive hormones are out of balance, this can hinder your ability to get pregnant. For an overview of your reproductive health and hormones in general, check out Mira’s Panorama Lab Test. This at-home finger-prick test provides you with insights into your fertility, ovarian reserve, thyroid functioning, and more – so that you can make informed decisions while TTC. 

You’ll also want to make sure you’re having sex at the right time each cycle when you are the most fertile. A great tool that can help you with this is the Mira App. Here, you can predict ovulation and log your periods – making it easy to track that LMP date when pregnant! The Mira App is so much more than just a cycle-tracking app, though. When paired with the Mira Monitor, you can track up to four key fertility hormones at home; allowing you to chart your unique 6-day fertile window, predict ovulation, and confirm that ovulation occurred.  

If you are having trouble balancing your hormones or figuring out your fertile window, you can always make an appointment at our Hormone Health Clinic for Fertility. Our experienced coaches can review your hormone charts, advise on healthy TTC habits and lifestyle choices, and provide emotional support throughout your TTC journey. 

Please note: Mira’s fertility coaches do not provide diagnoses, treatments, treatment adjustments, or medication prescriptions. Our services are not a substitute for a doctor’s advice, treatment plan, or diagnosis.

During Pregnancy 

After receiving a positive pregnancy test, make an appointment with your doctor immediately so they can help you plan for your pregnancy and delivery. After your initial appointment, make sure to attend all of your regular prenatal check-ups. These checkups are important because they involve tests and screenings to assess the health of your pregnancy – keeping both you and baby safe. 

Beyond medical support, you may also want to join a local or online pregnancy support group. Blogs like Motherly and The Bump can also be informative and comforting during pregnancy. 

After Pregnancy

After your baby is delivered, make sure to attend any post-natal checkups with your doctor. This is a safe space to discuss your health post-pregnancy and get additional support if needed. 

Navigating life with a newborn can be a challenge, and it’s important to take care of yourself during this time. Don’t be afraid to ask for help from friends or family, support groups, local charities, or even a counselor if you need it. Our own Hormone Health Coaches can also help you find balance in your new normal.  

Final Thoughts

The pathway to parenthood is a unique and special experience. If you are actively TTC, you may find our library of free webinars, ebooks, and blogs helpful for planning your pregnancy. You can also download the Mira App for free, which can assist with cycle tracking.   

If you are already expecting, check out our article Pregnancy Milestones Timeline for fun facts on what to expect each week during pregnancy. 

Frequently Asked Questions