Pregnancy Due Date Calculator
Calculate your pregnancy due date, trimester dates, and key milestones from your last menstrual period or conception date.
Frequently Asked Questions
How is the due date calculated?
The standard method (Naegele's Rule) adds 280 days (40 weeks) to the first day of your last menstrual period (LMP). This assumes a 28-day cycle with ovulation on day 14. If your cycle is longer or shorter, your due date may shift accordingly.
How accurate is a due date calculator?
Only about 5% of babies are born on their exact due date. Most births occur within 2 weeks before or after. Ultrasound dating in the first trimester (before 14 weeks) is the most accurate method and may adjust your due date.
What are the three trimesters of pregnancy?
The first trimester spans weeks 1–12, the second trimester weeks 13–27, and the third trimester weeks 28–40. Key milestones and screenings are scheduled around these periods.
What is gestational age vs. fetal age?
Gestational age counts from the first day of the last menstrual period (LMP), making the pregnancy about 2 weeks longer than fetal age, which counts from conception. Doctors and due date calculators use gestational age as the standard.