Use our Pregnancy Due Date Calculator to find out when your baby is due, and get started planning for that exciting arrival. Your doctor or midwife uses the number of weeks since your last menstrual period to estimate how far along you are in your pregnancy. This calculation is for an average pregnancy (40 weeks). Your pregnancy may be longer or shorter.
Only 5 percent of women deliver their babies on their projected due date. 10 percent of first time pregnancies continue on until two weeks past the due date. 70 percent of pregnancies that go post term are actually dated incorrectly from the start.
So this date should be used as an estimate; it is not an exact calculation.