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Pregnancy Due Date Calculator

Find your estimated due date, current week, and trimester

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Your Pregnancy Details

Estimated Due Date
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Current Week—
Trimester—
Days Remaining—
Days Pregnant—
Conception Estimate—

Development Milestones

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How Due Date Calculation Works

This calculator uses Naegele's Rule, which estimates the due date by adding 280 days (40 weeks) to the first day of your last menstrual period (LMP). If you know your conception date, we add 266 days (38 weeks) instead.

Only about 5% of babies are born on their exact due date. Most arrive within a 2-week window around the estimated date. Your healthcare provider may adjust the due date based on ultrasound measurements.

Frequently Asked Questions

How is the due date calculated?
The due date is calculated by adding 280 days (40 weeks) to the first day of your last menstrual period (LMP). This is called Naegele's rule. If using conception date, 266 days (38 weeks) are added.
How accurate is a due date calculator?
Only about 5% of babies are born on their exact due date. Most babies arrive within 2 weeks before or after. Early ultrasound dating (before 12 weeks) is the most accurate method.
What are the three trimesters?
First trimester: weeks 1-12 (organs form), Second trimester: weeks 13-26 (rapid growth, movement felt), Third trimester: weeks 27-40 (brain development, weight gain, preparation for birth).