Due Date Calculator (from LMP)

About this calculator

This version of a due date estimate works from the first day of the last menstrual period rather than an actual conception date, following the traditional method most commonly taught in prenatal care since conception itself is rarely known precisely. It adds the standard number of weeks associated with a full-term pregnancy counted from that starting point.

It's the calculation most people first encounter when a pregnancy is confirmed, since the LMP date is usually the one piece of information readily available without a scan. Healthcare providers and expecting parents alike use it as the initial reference date, which may later be adjusted based on ultrasound measurements.