Question: 12 mm gestational sac how many weeks?
Answer: Gestational Sac: Gestational age = 4 weeks plus (mean sac diameter in mm x days). This relies on the growth of the normal gestational sac of 1 mm per day after the 4th week of gestation. For example, a gestational sac measuring 11 mm would be approximately 5 weeks and 4 days gestational age.