Graphic design is often considered an artistic behaviour that is difficult to analyze rationally. With the development of research tools, it has become feasible to examine graphic design quantitatively. The objectives of this study are to define techniques that will quantify the simplification of graphics and to develop a systematic set of rules for graphic simplification. Through the three stages of the research process - ideation development of interval graphic simplification design, design practice, and discussion - this study presents four graphic simplification methods for the interval concept, namely: (a) grid simplification method, (b) node reduction method, (c) geon reduction method, and (d) blur method. This study proposes these techniques as viable methods to quantify and rationally analyze graphics, and hopes to provide valuable references for practitioners of graphic design, symbol design and computer-aided design (CAD) applications. The interval concept is the idea that the actual space between simplified graphics can be indicated by meaningful standard intervals.