Management of patients with aortic stenosis (AS) relies on accurate assessment of symptoms, AS severity, and left ventricular ejection fraction (LVEF). AS severity is best described by the measurements of maximum velocity, mean gradient, and valve area. In clinical practice, some patients have an apparent discrepancy in stenosis severity between those defined above. The continuous wave beam parallel to the stenotic jet should be taken using the best of multiple windows to avoid measurement error. Loading conditions influence velocity and pressure gradients; therefore, these parameters vary depending on cardiac output. Hence, no single calculated number should be relied on for final judgment. Evaluation of AS based on data obtained from echocardiography will play a more and more important role in the grading of AS.