Pregnancy Due Date Calculator
Estimate your due date from your last menstrual period or known conception date.
Estimate only — actual due dates are confirmed by your provider, typically with ultrasound.
Understanding your due date
Due dates are estimates, not promises. Only about 5% of babies arrive on the predicted date. Full-term is anywhere from 37 to 42 weeks; the 40-week target is an average. Early ultrasound measurements (before 14 weeks) give the most accurate estimate — typically within 5 days.
The due date is traditionally calculated from the first day of the last menstrual period (Naegele's rule: LMP + 280 days), assuming a 28-day cycle. This overstates actual gestational age by about 2 weeks since conception typically happens 14 days into the cycle. Don't panic if the baby arrives a week or two early or late — both are normal.