Free Pregnancy Due Date Calculator: Birth Predictor & Milestone Guide
Discover your baby's expected birthday and follow your pregnancy journey week-by-week. By using the standard medical 40-week gestation timeline, our tool provides a reliable estimate of your delivery date and key fetal development milestones.
Predict Your Due Date
Select the first day of your last period to see your baby's predicted arrival and key milestones.
FORMULA: Due Date = LMP + 280 DaysHow Due Date Calculation Works
In clinical obstetrics, the standard human gestation is calculated as exactly 280 days (40 weeks)from the first day of the last menstrual period (LMP). Our engine utilizes Naegele's Rule—a medically validated algorithm—to synthesize your estimated delivery date. This method accounts for the formative two-week pre-conception phase to provide a standardized timeline for prenatal care and developmental tracking.
What You'll Get
Weekly Milestone Timeline
View key developmental markers, from fetal heartbeat detection (Week 8) to anatomical viability (Week 24). Stay informed about each week of your journey.
Progress Visualization
Track your exact percentage of journey completion through real-time progress mapping. Understand your transition between the three primary trimesters.
Accuracy & Biological Windows
The predicted due date is an Estimated Arrival Coordinate, not a fixed appointment. Statistically, only 4% of babies are born on their exact due date, while 90% arrive within a two-week window of the prediction. For those curious about the exact moment their journey began, cross-reference your results with our Conception Date Finder. Always follow the personalized clinical advice provided by your obstetrician.
Common Questions
The 280-day (40-week) estimate is the obstetric gold standard for human gestation. While very few babies arrive exactly on their due date, most are born within a 10-day window of this prediction.
Our tool assumes the biological average of a 14-day ovulation gap. For irregular cycles, we suggest using your earliest positive test date or consulting a healthcare provider for an early dating ultrasound.
Pregnancy is divided into three phases: 1st Trimester (formative/organogenesis), 2nd Trimester (rapid growth), and 3rd Trimester (final preparation for birth). Each phase has unique physical and developmental markers.
Yes. If you know your exact conception date, you can add 266 days (38 weeks) to find your due date. Many professionals find this method more precise for certain biological timelines.
Most women don't know the exact day they conceived, but the first day of the last menstrual period (LMP) is usually a clear, documented date used to standardize pregnancy tracking.
Absolutely. We do not store or share any of your pregnancy data. All calculations happen locally in your secure browsing session.