Both the hardness and modulus values obtained by nanoindentation depend on knowledge of the area of contact between the test material and the indenter. Significant errors can be introduced into the measurement if the projected area of the indentation contact is not known with sufficient accuracy. The state-of-the-art for user validation of indenter area function is to use materials of known Young’s modulus in the ‘two reference materials method’. However, the area function is best measured directly by traceably calibrated metrological atomic force microscopy. An area function for a standard Hysitron indenter was generated, using both atomic force microscopy and indentation. The results are compared, and the effect of data fitting techniques and measurement uncertainty are discussed.