Pregnancy Due Date Calculator

How is the Due Date Calculated?

This calculator uses Naegele's rule, which is the standard method used by most healthcare providers to establish an Estimated Due Date (EDD).

The rule assumes a standard 28-day menstrual cycle, with conception occurring around day 14. To calculate the due date, it adds 280 days (40 weeks) to the first day of your Last Menstrual Period (LMP). If your average cycle length is longer or shorter than 28 days, the calculator adjusts the date accordingly.

The Trimesters of Pregnancy

A standard pregnancy lasts for roughly 40 weeks and is broken down into three trimesters:

• First Trimester (0 to 13 weeks): This is when the most crucial development occurs. The baby's body structure and organ systems begin to form.
• Second Trimester (14 to 27 weeks): Often called the "honeymoon period" of pregnancy, as early symptoms like morning sickness typically fade.
• Third Trimester (28 to 40+ weeks): The final stretch where the baby gains significant weight and prepares for birth.

Is the Due Date Accurate?

An estimated due date is exactly that—an estimate. It's completely normal to give birth a few weeks before or after your due date. In fact, only about 4% to 5% of babies are born exactly on their estimated due date.

Disclaimer: This tool is for informational purposes only. An ultrasound performed by a doctor in the first trimester is generally the most accurate way to date a pregnancy. Always consult your obstetrician for medical advice.