The normal size for an ascending aorta is approximately 33 millimeters in diameter. Because normal human anatomy varies, approximately 95 percent of the human population falls between 37 and 29 millimeters.
The ascending aorta is defined as the portion of the aorta arising from the aortic root and terminating into the aortic arch. Due to size of body and other factors, the average normal human ascending aorta is 33 millimeters. But differences exist between females and males. The normal female ascending aorta averages around 31.4 millimeters, and the normal male around 37.4 millimeters. Other factors which influence ascending aortic size include body size and age.