How to Use the Pregnancy Calculator
Calculate Your Due Date
Our pregnancy calculator uses the standard medical calculation method to estimate your due date. A typical pregnancy lasts 280 days (40 weeks) from the first day of your last menstrual period (LMP). This calculator provides three methods to determine your due date: using your LMP, conception date, or working backwards from a known due date.
Three Calculation Methods
- Last Menstrual Period (LMP): The most common and accurate method. Enter the first day of your last period, and the calculator adds 280 days to estimate your due date.
- Conception Date: If you know approximately when conception occurred, the calculator can work from that date. Conception typically happens about 14 days after the start of your last period.
- Due Date (Reverse): If your healthcare provider has given you a due date (perhaps from an ultrasound), you can enter it to calculate backwards and see your estimated LMP and conception date.
Understanding Trimesters
Pregnancy is divided into three trimesters, each lasting approximately 13 weeks:
First Trimester (Weeks 1-13)
Major organs begin to form. Common symptoms include morning sickness, fatigue, and breast tenderness.
Second Trimester (Weeks 14-27)
Often called the "honeymoon phase." Many women feel better. Baby grows rapidly and you may feel movement.
Third Trimester (Weeks 28-40)
Final preparations for birth. Baby gains most weight during this period. You may experience increased discomfort.
Important Note About Accuracy
While this calculator provides estimates based on standard pregnancy duration, every pregnancy is unique. Only about 5% of babies are born on their exact due date. Most babies are born between 37 and 42 weeks of pregnancy. Ultrasound measurements, especially those done in the first trimester, can provide more accurate due dates. Always consult with your healthcare provider for personalized medical advice and monitoring throughout your pregnancy.