Pregnancy Due Date Calculator

How to Calculate Due Date?

When you become pregnant, you may feel happy, excited, nervous—or all the above! It’s normal to experience these emotions and to want to begin preparing. More than likely, one of the first questions you’ll ask is when your baby will arrive.

Although every mother is different, there is a general timeline that pregnancies follow as far as due dates go, and you can determine your due date by a few different methods. Take advantage of the information and due date calculator from Club Mama to help you find out when your baby will come.

Date of Your Last Menstrual Cycle

One way to calculate your due date is by determining the date of your last menstrual cycle. Most pregnancies last around 280 days, or 40 weeks.¹

Count 40 weeks from the first day of your last period, and you’ll have an approximate due date for when your baby will arrive. Another method: subtract three months from the first day of your last period and add on seven days. 

For example, if the first day of your last period was September 16th, count back three months to June 16th, and add one year and seven days to that date. June 23rd is the approximate date you can expect your baby the upcoming year.

Conception Date

For most mothers, the exact conception date is almost never known. If you have a fairly regular menstrual cycle (around 28 days), conception typically occurs about 11–21 days after the first day of the last period.

However, knowing the exact date of conception is challenging because it’s difficult to know exactly when ovulation occurs. The exception is in cases of artificial insemination or in vitro fertilization, when women will typically know the exact date of conception—see IVF below for more details.²

Ultrasound Scan

Are you unsure when the first day of your last period was or when conception occurred? No worries, it happens! In this case, a pelvic ultrasound scan can help you determine your baby’s due date. 

If you haven’t had an ultrasound before, it’s a simple process in which the technician will either spread gel over your lower abdomen and press a tool (called a transducer) to it to examine your baby, or the transducer will be placed in your vagina to complete the exam. The type of exam you have is dependent on the types of images your doctor needs and why the exam is being done.³

IVF

If you’re one of the many moms using in vitro fertilization to become pregnant, there is another method you can use to determine your due date. Identify the date of the IVF transfer, and add 266 days.⁵

Since your doctor knows what day you actually conceived, predicting your due date with IVF can actually be more precise. That being said, there can still be some wiggle room around the date when your little one arrives. Using the ultrasound scan method throughout the course of your pregnancy will help you keep track of your baby’s progress as well.

Keep in mind that our pregnancy due date calculator and additional methods can indicate the approximate date your baby will arrive, but as far as the exact date goes, that’s up to your baby! Our tools and resource are here to help you plan and prepare, but there will always be some surprises in store. In the meantime, just relax, take care of yourself and enjoy the journey.

1. Cleveland Clinic. (2026, February 16). Pregnancy. Cleveland Clinic. https://my.clevelandclinic.org/health/articles/pregnancy
2. Calculating conception. American Pregnancy Association. (2026, January 30). https://americanpregnancy.org/getting-pregnant/calculating-conception/
3. Martel, J. (2016, October 7). Pregnancy ultrasound: Purpose, procedure & preparation. Healthline. https://www.healthline.com/health/pregnancy/ultrasound 
4. 4 Tanbo, T. G., Zucknick, M., & Eskild, A. (2018). Maternal concentrations of human chorionic gonadotrophin in very early IVF pregnancies and duration of pregnancy: A follow-up study. Reproductive BioMedicine Online, 37(2), 208–215. https://doi.org/10.1016/j.rbmo.2018.04.048