Due Date Calculator
Calculate your baby's due date using the first day of your last period or the date of conception.
One of the first questions every expectant parent asks is: "When will my baby arrive?" Our Due Date Calculator helps you answer that by estimating your delivery date based on the first day of your last menstrual period (LMP) or your conception date. While only about 4% of babies are born on their exact due date, knowing this date is vital for monitoring your baby's growth, scheduling prenatal tests, and preparing for labor and delivery.
Calculation Method
Your Due Date
Frequently Asked Questions
Understanding Your Due Date
Pregnancy math can be confusing. Because most women don't know the exact day they conceived, doctors calculate pregnancy starting from the first day of your Last Menstrual Period (LMP). This adds about two weeks to the pregnancy before you were actually pregnant!
1. When is a Baby "Full Term"?
Your due date marks 40 weeks of pregnancy. However, the American College of Obstetricians and Gynecologists defines term as:
- Early Term (37w 0d - 38w 6d): Fully formed but lungs may need more time.
- Full Term (39w 0d - 40w 6d): The "golden window" for best health outcomes.
- Late Term (41w 0d - 41w 6d): Overdue. Close monitoring required.
- Post Term (42w+): Delivery is usually induced to reduce risks.
2. How Accurate is This Calculator?
This calculator uses Naegele's Rule (LMP + 7 days - 3 months + 1 year), the global standard. However, it assumes a textbook 28-day cycle.
Irregular cycles: If your cycle is shorter or longer than 28 days, your actual due date might vary. An early ultrasound (dating scan) around 8-12 weeks is the most accurate way to date a pregnancy.
3. Can My Due Date Change?
Yes. If your first ultrasound shows the baby is significantly larger or smaller than expected based on your LMP, your doctor may revise your due date. This new date usually becomes the "official" one used for the rest of your care.
4. Frequently Asked Questions (FAQ)
Q: Is it safe to go past my due date?
Yes, many first-time moms go to 41 weeks. Your doctor will monitor the amniotic fluid levels and the baby's heart rate to ensure they are still thriving in the womb.
Q: Does IVF change the calculation?
Yes. For IVF pregnancies, the due date is calculated precisely from the date of egg retrieval or embryo transfer, which is far more accurate than LMP.