Calculation of the pregnancy due date or the expected date of delivery (EDD) of your baby is possible by using this unique pregnancy due date calculator. Just enter the 1st day of your last menstrual period below and you can find the expected date of delivery or your due date. Pregnancy, on average, lasts 267 days (38 weeks) from conception. If you positively know your conception date, you can add 267 days to it for your due date. A simple formula for calculation of your due date is also provided after this pregnancy due date calculator.