In Indonesia, an earthquake-prone area, building designs must be earthquake resistant, and using shear walls is one of the ways to make buildings more earthquake resistant. However, determining the requirements and optimal position of shear walls is difficult. Miscalculating in their positioning can cause torsion and other unpredictable behavior. Previous studies were done to know shear walls’ optimal areas and positioning. The first way was trial and error, but this method was ineffective and took a long time. The second way, MATLAB programming, is actually very effective since the needs and orientation of the walls can be determined precisely. Nevertheless, not all structural engineers and architects master the programming language. This study, therefore, proposes relatively simple formulas and procedures to determine the optimal area and positioning of shear walls for architects preliminary design during architecture design process. The accuracy test for the formulas and procedures was carried out using ETABS simulation experiments on 10 building models with various irregular categories. The result showed the formulas and procedures proposed in this study were quite accurate in calculating the needs and position of shear walls. Optimal conditions, furthermore, were quite easy to achieve in symmetrical geometric compositions (1 or 2 axes) while organic or random geometric compositions were quite difficult to achieve. When the use of shear walls achieves optimal condition, the strength and stiffness of a building are increased, and the distribution of its strength and stiffness is relatively even, hence anticipating deformation behavior and reducing building eccentricity.