🔵 Due Date Calculator for 30-Day Cycle — Free Online Tool
Calculate your due date calculator for 30-day cycle based on your last menstrual period (LMP). Get estimated due date, trimester breakdown, weeks pregnant, and 12 key milestones.
Frequently Asked Questions — Due Date Calculator
How is the due date calculated?+
The most common method is Naegele's rule: add 280 days (40 weeks) to the first day of your Last Menstrual Period (LMP). If your cycle is longer/shorter than 28 days, the calculator automatically adjusts.
How accurate is the estimated due date?+
LMP-based due dates are accurate to ±2 weeks for most pregnancies. Only 4% of babies are born exactly on their due date. An ultrasound at 8–12 weeks provides the most accurate dating.
What are the 3 trimesters of pregnancy?+
1st trimester: Weeks 1–13 (conception to 3 months). 2nd trimester: Weeks 14–27 (most comfortable period). 3rd trimester: Weeks 28–40 (preparation for birth). Full term begins at week 37.