How did you determine your due date

Ruth • I love jesus with all my heart.B/S Ex.Physio Nat`l Track All American- love sports, travel and helping change lives
Hey ladies, when you found out you were pregnant and were logging in your estimated due date in this app, did you go by the rule of the 40 weeks starting from the start of your last period or did you go by around the time you think you conceived? Thanks for the help!