Pregnancy and due date calculator
Estimate the due date and gestational age from the last menstrual period.
Estimated due date
March 25, 2027
Gestational age0 weeks and 1 days
Trimester1º
Naegele's rule: due date = last period + 280 days. Estimate — confirm with prenatal care.
How the calculation works
Naegele's rule adds 280 days (40 weeks) to the last menstrual period to estimate the birth. Gestational age is the time since that date.
Frequently asked questions
Is the due date exact?
It is an estimate; few babies are born exactly on the date. Ultrasound refines it.
Related calculators
Updated on June 17, 2026 · by Rafael Rossi · Methodology & sources