Pregnancy Due Date & Milestone Calculator
Estimate your baby's due date from the first day of your last menstrual period using Naegele's rule. Get your conception date, current gestational age, trimester, and key pregnancy milestones.
Naegele's Rule
Naegele's rule estimates a due date by adding 280 days (40 weeks) to the first day of your last menstrual period (LMP), assuming a standard 28-day cycle with ovulation around day 14. If your cycle is longer or shorter than 28 days, the estimate shifts by the same number of days to better reflect your actual ovulation timing.
Naegele's rule provides an estimate only — about 5% of babies are born on their exact due date, and a full-term pregnancy can range from 37 to 42 weeks. Early ultrasound measurements typically provide a more accurate due date, especially for irregular cycles. Always confirm your due date and milestones with your healthcare provider.
How to Use the Pregnancy Due Date Calculator
Enter the first day of your last menstrual period
Select the date your last period started (LMP). This is used as the starting point for all calculations.
Enter your average cycle length
The default is 28 days. If your cycles are typically longer or shorter, enter your usual cycle length for a more personalized estimate.
Click Calculate
See your estimated due date, conception date, current gestational age, trimester, and a timeline of key pregnancy milestones.
Real-World Scenario Example
"A last menstrual period started on January 1, 2026, with a typical 28-day cycle."
Inputs
Result
Estimated due date of October 8, 2026, with an estimated conception date around January 15, 2026. As of today, that's about 23 weeks and 3 days along, in the second trimester, with roughly 116 days remaining.
Important Disclaimer
This calculator provides a general estimate based on Naegele's rule for informational purposes only and is not a substitute for professional medical advice. Due dates, gestational age, and milestone timing can vary significantly between pregnancies. Always consult your healthcare provider for personalized prenatal care and accurate dating.
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