Cost estimation is a key part for any project planning. It's the process of predicting the quantity, cost, and price of the resources required for any project. The differences in construction methods between different forms of slabs result into variation in the cost of the slabs for any building project. Thus, this study aims at assessing the variation in construction cost among various construction methods available for four different types of floor slab systems. A 3D structural model had been analyzed and designed under a statically gravity loads by using computer software (ETABS v.16). In this study; a 3D model had been designed with different slab systems, solid, ribbed (one & two way), and flat plate slab. After that, quantity survey and cost estimate were done for each system, and a bill of quantity was constructed for each of them. Finally, the most economical system is selected; it is The Flat Plate Slab System.