The shear strength is one of the parameters that is used for the design of beam members in wood buildings. Shear strength is also used as a parameter for bridge girder design. Red meranti (Shorea spp.) is a species that is easily found in Indonesia and is commonly used as a construction material for buildings, docks, or bridges. The objective of this study is to obtain an empirical equation for the shear strength with different grain angles from 0° to 10°. The research of the influence of the grain angle must be carried out under real conditions, since the direction of the wood grain is not perfectly 0° and the inclination of the grain can influence the shear strength of the wood. The method of making the specimens and the experimental methods refer to ASTM D143-22, and the total number of test specimens was 33 specimens. The tests were performed using a universal testing machine, with the test speed (crosshead) 0.6 mm/minute. The test results show that the shear strength of wood with a directional fiber angle ranging from 0° to 10° in a range from 2.77 MPa (10° grain angle) to 7.57 MPa (0° grain angle). The results of the analysis by the polynomial regression method give an empirical equation, namely Fv = 7.03 − 0.97θ + 0.066θ2 with R-Sq = 74.7%. Fiber angle has an effect on shear strength. Empirical equations offer advantages to building designers in calculating the design capacity of wood beams, especially due to shear forces.