How Your Due Date is Calculated
A typical pregnancy lasts approximately 280 days (40 weeks) from the first day of your last menstrual period (LMP). Our calculator uses Naegele's Rule, a standard method of estimating the due date based on the assumption of a 28-day cycle.
The Trimester Breakdown
Pregnancy is traditionally divided into three stages, each with unique developmental milestones:
First Trimester
Weeks 1-12. Rapid development of major organs and structures.
Second Trimester
Weeks 13-26. The "Golden Period" where the fetus begins to move.
Third Trimester
Weeks 27-40. Final growth and preparation for delivery.
Why "Estimated" is Key
It is important to remember that only about 4% of babies are born on their exact due date. Factors such as cycle length, timing of ovulation, and individual health can influence the actual arrival date. Medical professionals will often refine this estimate using ultrasound scans during the first trimester.
Medical Disclaimer: This tool provides an estimate for informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment from your obstetrician or healthcare provider.