Aortic stenosis is the most common valvular heart disease with a prevalence of 2% among individuals over 65 years and 4% over 80, in developed countries. Accurate valve assessment for intervention timing is critical. Using only routinely obtained clinical data, this research aims to present accurate recreations of in vivo transvalvular hemodynamics using computational fluid dynamics (CFD) and validate Gorlin formula and echocardiography (echo)/continuity techniques. The in vivo valve was compared to simplified and idealized geometries. Instantaneous anatomic orifice area (AOA_max) was underestimated by about 40% by Gorlin's formula and (dP_mean). Time-averaged orifice area (EOA_mean), by an echo/continuity, was about 40% smaller than the AOA_max. The Gorlin formula better assesses AOA_max using (dP_{mean eff}). dP_{mean eff} is required for Gorlin formula approximation of AOA_max and echo/continuity overestimates EOA_mean with increasing error for lower flow rates. Correlations between EOA and AOA should only be made as instantaneous or only time-averaged comparisons.