The aim of the study is to assess the possibility of taking into account the granulometric composition of coke as one of the indicators characterizing its metallurgical properties. The main indicators of coke quality in real conditions change with forced or purposeful changes in the coal charge. When performing the study, data on the operation of blast furnaces and coke quality indicators were used in those periods when the coke strength reactivity and its granulometric composition changed. Based on a priori data on the effect of the CSR indicator on reducing the size of coke pieces in the reaction zone, an equation is proposed that takes into account both the equivalent diameter of coke pieces and the CSR indicator (a complex indicator of coke quality). The proposed indicator reflects to a greater extent the change in the working conditions of blast furnaces while changing the quality of coke.