Pregnancy Due Date Calculator
Estimate your due date, see how far along you are, and track key pregnancy milestones week by week.
Pregnancy Details
Standard is 28 days. Adjusts due date for longer/shorter cycles.
Estimated Due Date
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Current Progress
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Trimester
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Conception
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Days Left
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% Complete
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Pregnancy Progress
Baby Size This Week
Based on your current week
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Key Milestones
Week-by-Week Size Comparison
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Enter your details and click Calculate Due Date to see your results.
How Due Dates Are Calculated
This calculator uses Naegele's rule, the standard method used by healthcare providers. From your last menstrual period (LMP), it adds 280 days (40 weeks) to estimate your due date. If your cycle is longer or shorter than 28 days, the calculation adjusts accordingly.
Naegele's rule formula: LMP + 280 days + (cycle length - 28 days) = Estimated Due Date
For conception date, 266 days (38 weeks) are added. For IVF transfers, the calculation accounts for embryo age at transfer (3 or 5 days).
Important Notes on Accuracy
Only about 5% of babies are born on their actual due date. Most births occur within a window of two weeks before or after the estimated date.
First-time mothers tend to deliver slightly later than the due date on average. A "full term" pregnancy is considered anywhere from 37 to 42 weeks.
Ultrasound dating, especially in the first trimester, is typically more accurate than LMP-based calculations. Your healthcare provider may adjust your due date after an early ultrasound.
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Medical Disclaimer
This calculator is for informational and educational purposes only. It is not intended as medical advice, diagnosis, or treatment. Due date calculations are estimates. Always consult your OB-GYN or midwife for personalized prenatal care and accurate dating.
Last reviewed: March 2026 | Sources: Naegele's Rule, ACOG Practice Bulletin on Methods for Estimating Due Date