Calculate your estimated due date and pregnancy milestones from your last menstrual period or conception date.
Pregnancy Due Date Calculator
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Inputs
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Enter the first day of your last menstrual period.
Optionally enter your cycle length if different from 28 days.
Click Calculate to see your due date and pregnancy stage.
Naegele's rule: Due date = LMP + 280 days (40 weeks). Adjusted for cycle length variations. The due date is an estimate — only 5% of babies are born on their exact due date. Full term is 37–42 weeks.
Based on LMP, this is accurate within ±2 weeks. An ultrasound between 8–12 weeks provides the most accurate due date.