Calculate Your due date
Due Date Calculator
Please select the first day of you last period
You last period date:
Find out your due date with our pregnancy calculator, plus get info about your developing baby and see how big your baby is right now.
How we calculate your due date
Like most healthcare providers, we can calculate your due date by counting 40 weeks from the first day of your last period. If your cycle is consistently about 4 weeks long, that day is usually about two weeks before you conceive.
But if you happen to know the day you conceived – perhaps you were tracking your ovulation and you know the day your egg must have been fertilized – we can calculate your due date by counting 38 weeks from that date.
Your healthcare provider might revise your due date if she has reason to believe it’s off target. She’ll measure your baby during an ultrasound exam, and if your baby is much bigger or smaller than expected, she’ll provide you with a new due date.
Of course, your due date is just an estimate. Only 1 in 20 women delivers on her due date. You’re just as likely to go into labor any day during the two weeks before or after.