MSD Calculator
Convert mean gestational sac diameter (MSD) into an estimated early gestational age.
Mean sac diameter
Estimated gestational age
Total days
Estimated conception (approx.)
Estimated due date (from MSD)
Important: This calculator is for education only and is not a diagnosis. The formula (gestational age in days = MSD in mm + 30) is an approximation that is less precise than crown-rump length once an embryo is visible. Dating and any concern about the pregnancy should be assessed by your doctor or sonographer using the full scan.