The comparison of the determination of chemical composition distributions of butadi-ene-styrene copolymers, obtained by the formula method and experimental method of GPC, isgiven in this paper. The relative error of average compesition was shown to be less than 5%. Theformula method was found to be a more convenient and time-saving approach in the characteriza-tion of the copolymer composition distribution. The comparison of the determination of chemical composition distributions of butadi-ene-styrene copolymers, obtained by the formula method and experimental method of GPC, isgiven in this paper. The relative error of average compesition was shown to be less than 5%. Theformula method was found to be a more convenient and time-saving approach in the characteriza-tion of the copolymer composition distribution.