Due Date Calculator

Standard full-term pregnancies last approximately 280 days, or 40 weeks, starting from the first day of the last menstrual period (LMP). If using the LMP method, the calculation applies Naegele's rule adjusted for your specific cycle length: Birth Due Date = Date of LMP + 280 days + (Average Cycle Duration - 28 days). For conception-based tracking (CD), the arrival date is typically calculated by adding 266 days (38 weeks) directly to the known day of conception. Additional metrics like pregnancy week and percentage completion are derived by tracking the exact number of days remaining until your projected delivery milestone.

Imagine an expectant mother whose last menstrual period began on May 1st, and who has a standard 28-day menstrual cycle. To find her estimated delivery date, we add 280 days to May 1st. Factoring in standard calendar days across May, June, July, and subsequent months, the calculation lands on February 4th of the following year. Furthermore, if today is June 1st (31 days past LMP), the calculator determines she is currently in week 5 of her pregnancy, with 249 days left to go, marking roughly 11 percent completion of her full-term journey.

Keep a detailed record of your cycle lengths for several months prior to conception, as irregular cycles can shift your initial due date estimate. Remember that estimated delivery dates are statistical approximations; only about five percent of babies arrive precisely on their calculated day. Always consult your obstetrician or healthcare provider for an early ultrasound scan, which provides the most accurate clinical confirmation of your gestational age.