Due Date Calculator

This calculator estimates a pregnancy due date using the standard 280 day count from the first day of the last menstrual period. Enter that date and your average cycle length, and it returns the estimated due date, the likely conception date, the end of each trimester and the day full term begins at 37 weeks. A second tab works from a known conception date instead and counts 266 days forward. A cycle longer or shorter than 28 days shifts every date by the difference. Only about one birth in twenty lands on the estimated day, so this is a guide and not medical advice.