Pregnancy Due Date Calculator
Free pregnancy due date calculator — estimate your baby's due date, current pregnancy week, trimester, and key milestones from your last menstrual period (LMP) or conception date.
Estimate only — confirm with your healthcare provider. Ultrasound dating is more accurate.
How to use Pregnancy Due Date Calculator
- Enter the first day of your last menstrual period (LMP).
- Adjust cycle length if not 28 days.
- See your estimated due date (EDD), current week, and trimester.
Frequently asked questions
How is pregnancy due date calculated?
By Naegele's rule: add 280 days (40 weeks) to the first day of your last menstrual period. This calculator adjusts for cycles longer or shorter than 28 days.
How many weeks is a full pregnancy?
40 weeks from LMP, or 38 weeks from conception. Full-term is 37–42 weeks.
What trimester am I in?
First trimester: weeks 1–12. Second: weeks 13–27. Third: weeks 28–40+.
How accurate is the due date?
Only about 5% of babies arrive on the exact due date. Most arrive within 2 weeks before or after. An early ultrasound is the most accurate dating method.
Can I use this if I don't know my LMP?
Yes — switch to the conception date option and enter your estimated date of conception.
Is this calculator a substitute for a doctor?
No. Always confirm your due date with a healthcare provider — they will use ultrasound measurements for the most accurate estimate.