Pregnancy Due Date Calculator
Estimate your due date from the first day of your last period. Shows week-by-week trimester breakdown and key milestones. Uses Naegele rule with a 28-day cycle assumption.
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How to Use This Tool
- Enter the first day of your last menstrual period (LMP).
- Click 'Calculate' to see your estimated due date.
- View your current week of pregnancy and trimester information.
- See key milestones and important dates throughout your pregnancy.
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Frequently Asked Questions
How is the due date calculated?
The due date is calculated using Naegele's rule: add 280 days (40 weeks) to the first day of your last menstrual period. This is the standard method used by healthcare providers worldwide.
How accurate is the due date?
Only about 5% of babies are born on their exact due date. Most deliveries occur between 38-42 weeks. The due date is an estimate that helps track pregnancy progress and plan care.
What are the three trimesters?
First trimester: weeks 1-12 (organ development). Second trimester: weeks 13-26 (growth and movement). Third trimester: weeks 27-40 (final growth and preparation for birth).
Can I use this if I know my conception date instead?
Yes. If you know your conception date, add 266 days (38 weeks) instead of 280 days. The LMP method is more commonly used because conception dates are harder to pinpoint.