This tool calculates your pregnancy due date, an estimate of when you are likely to deliver your baby.
To find your due date, the calculator takes the first day of your last menstrual period (LMP) and adds 40 weeks. If you are planning a pregnancy, you can use this calculator to plan the birth for a certain month or season.
Katz VL (2008). Prenatal care. In RS Gibbs et al., eds., "Danforth's Obstetrics and Gynecology," 10th ed., p. 4. Philadelphia: Lippincott Williams and Wilkins.
Your due date is an estimate of when you will likely have your baby, based on the normal length of a full-term pregnancy. Most babies are born within 14 days of their due date.
Your health professional will also measure the size of your uterus and use ultrasound testing to determine your due date.