Enter your last period or conception date to instantly calculate your due date, current pregnancy week, and trimester.
Your due date is calculated by adding 280 days (40 weeks) to the first day of your last menstrual period (LMP). This is called Naegele's rule. If you know your conception date, add 266 days (38 weeks) instead.
The due date is an estimate. Only about 5% of babies are born on their exact due date. Most babies are born within 2 weeks before or after the estimated due date. Your healthcare provider may adjust the date based on ultrasound measurements.
A full-term pregnancy is 39–40 weeks. Babies born at 37–38 weeks are considered early term, 39–40 weeks are full term, and 41 weeks+ are late term. Babies born before 37 weeks are premature.