Enter the first day of your last menstrual period to estimate your due date and track your pregnancy progress.
How It Works
This calculator uses Naegele's rule, the standard method used by healthcare providers:
Due Date = LMP + 280 days (40 weeks)
- Pregnancy is dated from the first day of your last menstrual period (LMP), even though conception typically occurs about 2 weeks later.
- A full-term pregnancy is approximately 40 weeks or 280 days from LMP.
- Only about 5% of babies are born on their exact due date. Most are born within 1-2 weeks before or after.
- The first trimester spans weeks 1-12, the second trimester weeks 13-26, and the third trimester weeks 27-40.
This calculator provides an estimate only. Your healthcare provider may adjust your due date based on ultrasound measurements or other factors.