Estimate a baby's due date and conception date from the first day of the last period.
A typical pregnancy lasts about 280 days, or 40 weeks, counted from the first day of the last menstrual period. The due date is that span added to the LMP, while conception is estimated about two weeks later when ovulation usually happens. Knowing the approximate due date sets the timeline for prenatal visits, ultrasound scans and maternity leave planning, so it is one of the first numbers an expectant family wants.
Due Date
Due date = first day of last period + pregnancy length (usually 280 days); conception ≈ LMP + 14 days
Due dates are estimates; only about four percent of babies arrive exactly on the calculated date.
Due date = first day of last period + pregnancy length (usually 280 days); conception ≈ LMP + 14 days A typical pregnancy lasts about 280 days, or 40 weeks, counted from the first day of the last menstrual period. The due date is that span added to the LMP, while conception is estimated about two weeks later when ovulation usually happens.
Knowing the approximate due date sets the timeline for prenatal visits, ultrasound scans and maternity leave planning, so it is one of the first numbers an expectant family wants.
This calculator takes 4 inputs: LMP year, LMP month, LMP day, Pregnancy length (days). The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.