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Due Date Calculator

Calculate your estimated due date, current pregnancy week, and key milestones.

Last Menstrual Period
Conception Date
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Estimated Due Date
Current Week
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Trimester
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Weeks Remaining
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Countdown
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Key Milestones by Week

WeekMilestone

About the Due Date Calculator

This due date calculator estimates your expected delivery date based on either the first day of your last menstrual period (LMP) or the date of conception. A full-term pregnancy lasts approximately 40 weeks (280 days) from LMP, or 266 days from conception. The calculator also shows your current pregnancy week, trimester, weeks remaining, and a countdown to the due date.

How the Due Date Is Calculated

From LMP: Due Date = LMP + 280 days (40 weeks)
From Conception: Due Date = Conception + 266 days (38 weeks)

Trimester breakdown: First = weeks 1–13, Second = weeks 14–27, Third = weeks 28–40

How accurate is the due date?

Only about 4% of babies are born on their exact due date. Most deliveries occur between 37 and 42 weeks. The due date is an estimate used for planning and monitoring fetal development. Your healthcare provider may adjust it based on early ultrasound measurements.

What is the difference between LMP and conception date?

The LMP method counts from the first day of your last period (about 2 weeks before ovulation). The conception date method counts from fertilization. The LMP method is more commonly used because conception dates are often unknown. For a regular 28-day cycle, ovulation and conception occur around day 14, which is why the LMP due date is 280 days while conception is 266 days.