Estimated due date and gestational age.
Estimate the due date, current gestational age, and trimester from the first day of the last menstrual period and the user's typical cycle length.
Naegele's rule: due date = first day of LMP + 280 days, adjusted by (cycle length − 28) days for non-28-day cycles.
Estimate the due date, current gestational age, and trimester from the first day of the last menstrual period and the user's typical cycle length.
It is an estimate. A first-trimester ultrasound is the most accurate way to date a pregnancy and should override LMP-based estimates.
Our editors read every message. If the math looks off, tell us the inputs you used and what you expected.
