Health & Fitness
Due Date Calculator
Estimate your baby's due date, find out your current pregnancy week, and track which trimester you're in — all from your last menstrual period.
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How is the Due Date Calculated?
The Estimated Due Date (EDD) is calculated using Naegele's Rule, which adds 280 days (40 weeks) to the first day of your last menstrual period (LMP). This assumes a standard 28-day cycle. Our calculator adjusts for different cycle lengths by adding or subtracting days accordingly.
The Three Trimesters of Pregnancy
- First Trimester (Weeks 1-13): The embryo develops all major organs. Morning sickness and fatigue are common. Highest risk of miscarriage in this period.
- Second Trimester (Weeks 14-26): Baby begins to move. Energy typically returns. Gender can be determined via ultrasound.
- Third Trimester (Weeks 27-40): Baby gains weight rapidly and prepares for birth. Braxton Hicks contractions may begin.
👶 Important Note
Only about 5% of babies are born on their exact due date. Most births happen within 2 weeks before and after the EDD. Always consult your OB/GYN or midwife, as early ultrasound dating is more accurate than LMP calculations.
Frequently Asked Questions
Only about 4% of babies are born on their exact estimated due date. The EDD simply marks the 40-week milestone; a normal full-term delivery can occur anywhere between 37 and 42 weeks.
Because exact ovulation and conception dates are difficult to pinpoint, doctors internationally use the LMP rule (Naegele's rule) as a standardized chronological starting marker.
Yes. Naegele's rule assumes a standard 28-day cycle with ovulation on day 14. If your cycle is significantly shorter or longer, ultrasound dating will provide a much more accurate timeline.