Due Date Calculator

A due date calculator estimates your baby's birth date based on your last menstrual period (LMP). The standard medical method uses Naegele's Rule, which adds 280 days (40 weeks) to the first day of your last period. The first 14 days are the follicular phase before ovulation, and conception typically occurs around day 14 after your LMP. The due date is an estimate — only about 5% of babies are born on their exact due date, and most arrive between 37 and 42 weeks, which is considered normal.

1. 1. Select the first day of your last menstrual period using the date picker
2. 2. The calculator will automatically compute your due date, current pregnancy week, and progress
3. 3. Review your due date and the three trimester stages

First Trimester (Weeks 1-12)

A critical period for embryo implantation and organ formation. Your baby develops from a fertilized egg into a fetus with a recognizable human form. Avoid harmful substances, take prenatal vitamins with folic acid, and expect common early pregnancy symptoms like morning sickness.

Second Trimester (Weeks 13-27)

Your baby grows rapidly and organs continue to mature. You may start feeling fetal movements. Morning sickness typically eases, appetite returns, and this is often the most comfortable phase. Schedule important prenatal screenings like the anatomy scan around week 20.

Third Trimester (Weeks 28-40)

Your baby gains weight quickly and organ systems mature. At 37 weeks, your baby is considered full term and could arrive at any time. Watch for signs of labor such as regular contractions, bloody show, or water breaking. Prepare your hospital bag and birth plan.