Abstract <p>Young’s modulus (elastic modulus) of ceramics is a fundamental property that influences the mechanical characteristics of the material. When designing a ceramic material, a large number of experiments are required to determine the influence of phase composition on the elastic modulus. To quickly select the composition of a composite, it would be optimal to calculate its properties; however, today, there is no consensus on the dependence of Young’s modulus of composite materials consisting of brittle components on their composition. This paper proposes an equation for calculating the elastic modulus of a diamond–silicon carbide composite, which includes its phase composition, elastic moduli of the phases, composite porosity, and pore shape factor, which allows for a fairly accurate prediction of the material’s properties.</p>