This calculator provides an estimate only based on Naegele's Rule. Only about 5% of babies are born on their exact due date. Most deliveries occur within two weeks before or after the estimated due date.
This tool is for informational purposes only and does not constitute medical advice. Always consult your healthcare provider for accurate pregnancy dating, which may include ultrasound measurements and clinical assessment.
Naegele's Rule: The due date is calculated by adding 280 days (40 weeks) to the first day of your last menstrual period (LMP), adjusted for your cycle length.
Cycle Length Adjustment: If your cycle is longer or shorter than 28 days, the due date is adjusted accordingly. For example, a 30-day cycle adds 2 extra days.
Conception Date Method: If you know your conception date, we subtract 14 days to estimate the equivalent LMP, then apply Naegele's Rule.