A pregnancy due date is typically estimated by adding 40 weeks (280 days) to the first day of the last menstrual period (LMP), assuming a regular 28-day cycle. This estimate is used by doctors to guide prenatal care but is only an approximation, as birth can occur a few weeks before or after the due date. To know your specific due date, you need to provide the first day of your last menstrual period or the date of conception if known. If you want, a pregnancy calculator can help you estimate it based on this information. If you provide the date of your last menstrual period or conception, I can help calculate your estimated due date more precisely. Otherwise, the general method is adding 40 weeks to the LMP date for a rough estimate.