Pregnancy Due Date (LMP)
Classic Naegele rule: EDD = first day of LMP + 280 days.
Calculator
How it works
Naegele’s rule is a historical 28-day-cycle shortcut used for teaching and quick estimates. Clinical obstetric dating follows guideline-based ultrasound and last-normal-period adjustments.
Limits
Irregular cycles, hormonal contraception, breastfeeding amenorrhea, and early pregnancy loss can invalidate LMP-only dating. This tool does not provide obstetric management.
Educational tool only—not for diagnosis or treatment decisions.