The work addresses the question of the field-dependence of the notional emission area for a field-emitter tip using computer simulation and experimental data. Based on finite-element method calculations, it was determined that for single field emitters having a given shape, there is a stable and characteristic shift of the degree of voltage in the pre-exponential voltage exponent of the field emission equation relative to the “planar” case. A power-law fit to the 3D-data was applied so as to use it in the analysis of the current-voltage data using a k-power plot (KP-plot) of semilogarithmic type. A comparison of effective emission parameters obtained from the model current-voltage characteristic with the classical Fowler–Nordheim plot, modern Murphy–Good plot, and new KP-plot is carried out. The KP-plot is subsequently used to analyze the experimental data of Tungsten emitters having a scanning emission microscope determined apex radius. The new semilogarithmic analysis reveals that the apex radius of curvature is within the observed range.