This thesis investigates the influence of indenter geometry and force misalignment on hardness measurements. Solid and analytical geometry models are developed for the Brinell, Vickers, and Knoop methods to describe how specific geometrical parameters and the alignment of the applied force affect the indentation geometry and the resulting hardness values. Both approaches are derived from the same geometrical framework but differ in the boundary conditions imposed on the indentation process and in their metrological interpretation. The analytical results are compared with experimental data to validate the models and propose correction approaches aimed at improving the metrological reliability of hardness testing procedures.