Take the date of your last period, add 40 weeks. If you can’t remember it, try to remember the date of the last fight you had with your husband (it’s probably around then).
Subtract two weeks if you are having twins.
Add two weeks if you are known for being chronically late. And an extra one if you are 35 weeks pregnant and still haven’t found a doctor who “supports your birth plan.”
Add another week if you like to over-think things. On second thought, maybe subtract a week. No, wait…definitely add one.
Subtract a week and a half if your feet are really swollen and you can’t wait to get this baby out of you.
Subtract three days if your husband asked that your impending labor not “ruin St. Patrick’s Day” for him.
Add a week if you won tickets to a Bon Jovi concert on your actual due date, and you really, really want to attend.
Add another week if your sister requested that you not have your baby on her birthday.
Congratulations; you have successfully calculated your exact due date. Your baby will arrive sometime within six weeks before or after that date. So happy planning!