 This paper proposes two methods for determining the minimum and maximum reinforcement ratios for hybrid glass fiber reinforced polymer, GFRP, slash steel reinforced concrete beams to prevent sudden and brittle failure as well as the compression failure of concrete before the tension failure of reinforcements. The first method uses equilibrium equations to determine the minimum hybrid GFRP slash steel reinforcement ratio, while the second method uses equilibrium equations to determine the maximum hybrid GFRP slash steel reinforcement ratio. Both methods are then applied to estimate the load-carrying capacity of concrete beams reinforced with hybrid GFRP slash steel. The proposed methods show good agreement with experimental data and existing test results in the literature, with a maximum discrepancy of 7%. This article was authored by Duwei Fan Guin and Viet Quoc Dang.