Count 40 weeks from the first day of your last menstrual period
Add 280 days to the first day of your last menstrual period
Subtract 3 months from the first day of your last menstrual period, then add 7 days
Use the date of conception if known, then add 38 weeks
Use the date of ovulation if known, then add 38 weeks
Use an early ultrasound for the most accurate estimate
Ask your healthcare provider to confirm the due date
Remember that only about 5% of babies are born on their exact due date