We derive a general contact-depth function for the Vickers indenter by modifying a scaling relation
between yield strain and indentation depth ratio, which is comprised of indenter angle,plastic
constraint factor, and indentation depth ratio.The validity of this function is demonstrated by using
various indenters of different angles.A method for calibrating the actual contact area of an imperfectly
shaped Vickers indenter is suggested that yields a better evaluation of Vickers hardness in the
instrumented indentation test.