The main aim of this study is to examine the effect of area on color harmony in interior spaces. Area in color harmony is the relative amount of different color areas represented as a proportion on which color harmony depends. Colors in the color scheme of an interior space are usually not applied in equal proportions of surface areas and considering the complex relations of colors in interior spaces, it is important to search for the principles of color harmony and area effects in interiors. The secondary aim of the study is to investigate how the term color harmony was defined and the link between color harmony and related terms used to define it. The related terms that are used to define color harmony can explain why a color scheme is evaluated as harmonious. In this study, three primary (red, blue, yellow) and three secondary (green, purple, orange) colors of Itten’s color wheel were studied in a simulated office interior with three-color schemes emphasizing different proportional use of each color. There were four color combinations, each consisting of six images differing in areas of the constituent colors. Firstly, participants evaluated the harmony content of the images by comparing them in pairs. Secondly, they evaluated each image regarding the thirteen terms related to color harmony. Findings indicated that area had an effect on color harmony for two of the color combinations (warm and cool color schemes). However, there were no strong but rather moderate and weak correlations between color harmony and the terms.