Calculate your due date, pregnancy timeline, and track your baby's development week by week with our comprehensive pregnancy calculator.
Pregnancy calculations are based on several key factors that help determine your due date and track your baby's development throughout the pregnancy journey.
Pregnancy is typically calculated from the first day of your last menstrual period (LMP), not from the actual conception date. This is because:
Critical period of development. Major organs and systems begin to form. Morning sickness and fatigue are common.
Often called the "golden period." Baby's movements become noticeable, and most women feel their best.
Final growth phase. Baby gains weight rapidly, and preparation for birth begins.
Several factors can influence the accuracy of your calculated due date:
Each week of pregnancy brings new developments for your baby:
While pregnancy calculators provide helpful estimates, remember:
Pregnancy due date calculators are generally accurate within 3-5 days for women with regular 28-day cycles. However, only about 5% of babies are born on their exact due date. Most babies are born within 2 weeks before or after the due date.
If you have irregular periods, the LMP method may be less accurate. In this case, an early ultrasound (before 20 weeks) is the most reliable way to determine your due date. Your healthcare provider can help establish the most accurate dating.
Yes, if you know your conception date, you can add 266 days (38 weeks) to get your due date. However, the LMP method is still preferred as it's more standardized and accounts for the typical 14-day period between LMP and ovulation.
Gestational age is measured from the first day of your last menstrual period and is what healthcare providers use. Fetal age is the actual age of the baby and is typically about 2 weeks less than gestational age.
Your due date typically doesn't change once established by your healthcare provider. However, you can use pregnancy calculators throughout your pregnancy to track your progress, see what week you're in, and learn about your baby's development.
It's normal for babies to measure slightly ahead or behind the calculated due date. Your healthcare provider will monitor your baby's growth and may adjust the due date if there are significant differences, especially in early pregnancy.