The microstructural dependence of the mechanical properties of Ca-modified lead titanate piezoelectric ceramics were studied. To this end, a combination of the Vickers and Knoop indentation techniques at different applied loads was used as simple method for mechanical characterization of these ceramics. The influence of porosity, grain size and tetragonal distortion on hardness, Young’s modulus and toughness is discussed. An attempt to obtain internal stresses from toughness variation reveals the limitations of the method.