Calculate your estimated due date based on your last menstrual period. Free online pregnancy due date calculator with trimester breakdown.
The pregnancy due date calculator estimates your expected delivery date based on Naegele's rule, which adds 280 days (40 weeks) to the first day of your last menstrual period (LMP). This is the standard method used by healthcare providers. Pregnancy is divided into three trimesters: First (weeks 1-13), Second (weeks 14-27), and Third (weeks 28-40).
Due Date = LMP + 280 days (40 weeks)Naegele's rule calculates the estimated due date by adding 7 days to the first day of the LMP, subtracting 3 months, and adding 1 year. The simpler equivalent is adding 280 days to the LMP date. This assumes a regular 28-day menstrual cycle.
| Input | Output |
|---|---|
| LMP: January 1, 2024 | Due: October 7, 2024 | ~40 weeks |
| LMP: June 15, 2024 | Due: March 22, 2025 | ~40 weeks |
| LMP: March 1, 2024 | Due: December 6, 2024 | ~40 weeks |