The EN AB-46000 alloy castings are widely used in automotive industry due to their relative good strength combined with a low density and an excellent conductivity. Porosity of EN AB-46000 alloys is one of the most important defects, responsible for the low strength and poor plastic properties of castings as well as their tightness. Quantitative porosity measurement were performed using quantitative metallography and image analysis methods using ImageJ. The study shows that such parameters of high-pressure die casting are the piston speed in the second casting phase and the final pressure increase in the pressing phase. It has been shown that the appropriate selection of these parameters can significantly reduce the porosity of castings made of alloy EN AB-46000.