Due Date Calculator

Estimate your baby's expected arrival date with our accurate pregnancy calculator

Calculate Your Due Date

About Due Date Calculation

A due date calculator helps estimate when your baby might arrive based on key dates in your pregnancy. Only about 5% of women deliver on their exact due date, but it serves as an important reference point for prenatal care.

How Due Dates Are Calculated

Our calculator uses the Naegele's rule, the standard medical formula for estimating due dates:

  • Last Menstrual Period (LMP): Due date = LMP + 280 days (40 weeks)
  • Conception Date: Due date = Conception date + 266 days (38 weeks)
  • Ultrasound Dating: Uses fetal measurements from early ultrasound for most accurate dating

Why Due Dates Vary

Only about 5% of women deliver on their exact due date. A normal pregnancy can last anywhere from 37 to 42 weeks. Factors like irregular cycles, ovulation timing, and fetal development can all affect the actual delivery date.

Pregnancy Trimesters Explained

First Trimester

Weeks 1-12: Major fetal development occurs. Morning sickness and fatigue are common.

Second Trimester

Weeks 13-26: Often the most comfortable period. Fetal movement begins.

Third Trimester

Weeks 27-40: Final growth and development. Preparation for delivery.