Estimate your due date and track important pregnancy milestones
The Pregnancy Calculator helps you estimate your due date (also known as the estimated date of delivery or EDD) based on your last menstrual period, conception date, or IVF transfer date. It also provides information about important pregnancy milestones.
The calculator uses different methods to estimate your due date:
This is the most common method used by healthcare providers. It's based on Naegele's rule, which calculates the due date by adding 280 days (40 weeks) to the first day of your last menstrual period. The calculation also adjusts for cycle length.
If you know your conception date, the calculator adds 266 days (38 weeks) to that date to estimate your due date. Conception typically occurs about 14 days after the start of your last period.
For IVF pregnancies, the due date is calculated based on the transfer date and the age of the embryo at transfer (typically 3 or 5 days after fertilization).
Fertilization occurs, and the fertilized egg implants in the uterine lining. By the end of the 4th week, the embryo is about the size of a poppy seed.
The embryo's heart begins to beat, and facial features start forming. By the end of the 8th week, the embryo is about the size of a kidney bean.
The embryo is now called a fetus. All essential organs have formed, and the fetus can move. By the end of the first trimester, the fetus is about 3 inches long.
The fetus starts forming facial expressions, and you might begin to feel movements. Gender can usually be determined by ultrasound.
The fetus develops a regular sleep-wake cycle and can hear sounds. The anatomy scan (20-week ultrasound) is typically performed during this time.
The fetus has a chance of survival if born prematurely. Lungs begin developing surfactant, which helps them inflate after birth.
The fetus can open eyes and has more defined sleep patterns. Brain growth accelerates, and the nervous system develops rapidly.
The fetus gains weight rapidly, and bones fully develop. Most babies turn head-down in preparation for birth.
The fetus continues to gain weight and develop. Lungs are nearly fully developed, and the baby drops lower in the pelvis.
The baby is considered full term and ready for birth. Most babies are born within a week before or after the estimated due date.
Only about 5% of babies are born exactly on their due date. A normal, full-term pregnancy can last anywhere from 37 to 42 weeks. This calculator provides an estimate only and should not replace medical advice. Always consult with healthcare providers for personalized information about your pregnancy.