How To Compute Due Date In Pregnancy?

Use the first day of your last menstrual period (LMP)

Add 280 days, or 40 weeks, to the LMP date

Use Naegele’s rule: subtract 3 months from the LMP date, add 7 days, and add 1 year if needed

If you know the conception date, add 266 days, or 38 weeks

Use an ultrasound date estimate if the LMP is unknown or cycles are irregular

Confirm the due date with your healthcare provider