Understanding Due Date
The due date calculator estimates your expected delivery date based on the first day of your last menstrual period. Knowing your estimated due date helps you prepare for your baby's arrival, schedule prenatal appointments, track developmental milestones, and plan maternity leave. The standard calculation uses Naegele's rule, which adds seven days to the first day of your last period, adds one year, and subtracts three months, resulting in a due date approximately forty weeks or two hundred eighty days from the last menstrual period. This calculator performs this computation instantly and shows your due date along with the current gestational age in weeks and days. It also provides a trimester breakdown showing important milestones throughout your pregnancy. The first trimester spans weeks one through twelve and is when major organ systems develop. The second trimester from weeks thirteen through twenty-six is often called the honeymoon period as early pregnancy symptoms ease. The third trimester from week twenty-seven to birth is when the baby grows rapidly and final development occurs. Remember that only about five percent of babies arrive exactly on their due date, which is why it is called an estimated date. Most births occur within two weeks before or after the calculated date. Use this free due date calculator to estimate and track your pregnancy timeline.