Fluidity of cast metals are typically measured by the length of metal that is stopped by the solidification where the filling is carried out at a constant cross sectional mold cavity. In this work, a sand mold geometry with different section thicknesses were used to measure the fluidity characteristics of A356 alloy at various casting temperatures (700, 725, 750 A degrees C) with and without modifications. It was found that Ti modification had no significant effect on fluidity. On the other hand, the highest fluidity was achieved by Sr modification even at low pouring temperatures. The results were compared with simulation software (SolidCast), and critical fraction of liquid (CFL) was determined.