This paper proposes a simple model that can reasonably determine the potential plastic hinge region for seismic design of shear walls. To idealise the plastic hinge region, a parametric study is conducted on the curvature distribution over the member length using a non-linear, two-dimensional, finite-element analysis procedure. To solve the plastic hinge length equation derived from the idealised curvature distribution, the equations for yielding and ultimate moment capacities of shear walls are generalised on the basis of Bernoulli's principle, strain compatibility condition and equilibrium condition of forces. The generalised equations promise that the yielding and ultimate moment capacities of shear walls can be straightforwardly evaluated with relatively high accuracy. Ultimately, the plastic hinge length of the shear wall is then simply formulated as a function of longitudinal tensile reinforcement index in the boundary element, vertical shear reinforcement index in the web, and axial force index. The predicted plastic hinge lengths obtained from the current simple model are in better agreement with test results than the previous equations; the mean, standard deviation and coefficient of variation of the ratios between experiments and predictions are 1·019, 0·102 and 0·100, respectively.