Due Date Calculator
Calculate your expected due date, conception date, and pregnancy milestones with our accurate pregnancy due date calculator.
Category: Fitness & Health
Due Date Calculator
Enter your information to calculate your baby's due date and important pregnancy milestones.
Frequently Asked Questions
How is the due date calculated?
The due date is commonly calculated using Naegele's rule, which adds 280 days (40 weeks) to the first day of your last menstrual period (LMP). If calculated from conception, we add 266 days (38 weeks) to the conception date. Ultrasound dating is based on fetal measurements that correspond to specific gestational ages.
How accurate is the due date calculator?
Only about 5% of babies are born exactly on their due date. Most babies are born within 2 weeks before or after the calculated due date. Ultrasound dating in the first trimester (before 14 weeks) is generally more accurate than LMP dating, especially for women with irregular cycles.
What if I don't know the date of my last period?
If you don't know your last period date but know when conception occurred (such as with fertility treatments), use the conception date calculation. If neither is known, an early ultrasound is the best way to determine gestational age and due date.
What does 'full term' mean?
Full term is defined as a pregnancy that has reached 39 weeks to 40 weeks and 6 days of gestation. Early term is 37 weeks to 38 weeks and 6 days, and babies born during this period may have slightly increased risks of respiratory and other issues. A pregnancy is considered post-term after 42 weeks.