Pregnancy Due Date Calculator

Estimate your due date based on your last menstrual period (LMP).

First Day of Last Menstrual Period

How Due Date is Calculated

This calculator uses Naegele's Rule: add 280 days (40 weeks) to the first day of your last menstrual period. This is an estimate — only about 5% of babies are born on their exact due date. Most births occur between 38-42 weeks.