The article presents an innovative decision-making strategy for determining the scale ratio between art objects and interior space, aimed at enhancing the spatial perception of art and interior design. The study employed a structural approach, which included a critical analysis of theoretical and practical materials, experimental design, on-site measurements of the primary scale ratios between art objects and interiors, as well as the involvement of respondents for visual evaluation of the data. An analytical approach was also used to systematize, generalize and compare the collected data. The study identified numerical coefficients that define scale levels, offering a structured approach to making design decisions. As a result, three universal levels of optimal scale relationships between art objects and interior space were formulated, which can be used in designing interiors of various sizes: I Max - for large spaces of public interiors; II Intermediate - for small spaces of public and residential interiors; III Min - for small spaces of residential interiors. The implementation of the obtained results demonstrated the effectiveness of the developed approach and allowed us to conclude that for interior designers it can become a tool that allows creating functionally efficient and maximally harmonious spaces for human life.