In this work, the total and plastic hardness of a variety of materials were determined from the work-of-indentation. We show that by taking into account the influence of the tip defect, both the total and plastic hardness have the same values and that the hardness-load dependence is considerably reduced, thus explaining that part of the indentation size effect can be related to an incorrect estimation of the tip defect. To consider the influence of the indenter tip defect, we propose a calculation of the impression volume involving the length of the truncated indenter tip. For the residual impression volume, we have demonstrated that it can be simply calculated from the total volume using a proportionality constant equal to the residual to maximum depth ratio. Moreover, the hardness derived from work-of-indentation is found to be equal to the Meyer hardness. Finally, the ratios of Meyer hardness to the reduced modulus and elastic work to total work of indentation are found to be very close to the proportionality factor (π tanα) of Stilwell and Tabor.