How to Calculate Your Pregnancy Due Date
The most common method is Naegele's Rule: add 280 days (40 weeks) to the first day of your last menstrual period (LMP). This calculator also adjusts for cycle lengths other than the standard 28 days.
First Trimester
Weeks 1–12. Critical development period. Most early pregnancy symptoms occur here.
Second Trimester
Weeks 13–26. Often the most comfortable phase. Baby movements begin.
Third Trimester
Weeks 27–40. Rapid growth. Preparation for birth begins.
Full Term
Weeks 39–40. Baby is considered full term and ready for birth.
Who Should Use This Tool?
This calculator is designed for expectant parents who want a quick estimate of their due date and pregnancy milestones. It is useful for initial planning before your first prenatal appointment, where an ultrasound will provide a more accurate date.
Limitations
Due date calculations are estimates based on average cycle lengths and standard formulas. Actual delivery dates vary widely. Ultrasound dating, especially in the first trimester, is more accurate. This tool does not replace medical advice.