Bulk Fe_1−xGa_x alloys present a strong sensitivity of the magnetostrictive properties with Ga content with maximum magnetostriction near x = 0.19. Here, we present magnetoelastic coefficients measured by the cantilever method on Fe_1−xGa_x thin films grown by molecular beam epitaxy on GaAs(001). We find that Ga-dependent magnetoelastic coefficients in nanometer thin films are comparable in magnitude to the respective bulk values. Moreover, we compare thin films with a tetragonal structure due to a slightly preferential alignment of Ga pairs along the growth direction with and a cubic structure. It turns out that magnetoelastic coefficients are unaffected by a preferential alignment of Ga pairs along the growth direction.