Pregnancy Due Date Calculator

Estimate your due date using your last menstrual period, conception date, or an ultrasound scan.

First day of last period

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About this calculator

This calculator uses Naegele's rule: due date = last period start + 280 days, assuming a typical 28-day cycle. Conception-based estimates add 266 days; ultrasound-based estimates add the remaining days to reach 280 total.

This is a statistical estimate, not a guarantee — only about 5% of babies are born exactly on their due date. This tool doesn't replace medical advice.