Pregnancy Calculator: How to Determine Your Due Date!

Are you looking to calculate your due date?

Determining when your due date is could be a chore. The average pregnancy is usually 266 days from your date of conception or 280 days away from your last menstrual cycle.

Who invented this method?

Around 1850, Dr. Naegele estimated that the average length of pregnancy was around 9 months. He assumed that the average woman had a 28 day cycle and that she ovulated on day 14. With these facts he created this formula:

((LMP + 7 days) - 3 months) = Due Date

EX: ((January 1, 1996 + 7 days) - 3 months) = October 8, 1996

While this isn’t exactly the best method we still use this formula today. Since then we’ve found out that there are different circumstances that may change your due date. For example, ethnicity, parity, prenatal care, nutrition and ovulation day can change from person to person.

Want to see when your baby is due?

Check out Surebaby’s pregnancy calculator here!