The surface:areas of Pt and Pt-Ru alloys have been estimated by a fractal technique. Fractal measurements were made using a scanning tunneling microscope (STM), which measures the surface corrugations. This STM-based fractal-technique is offered as an alternative to gas adsorption technique;for area estimation. The usefulness of the fractal approach to area calculation in the Pt-Ru alloy, where the hydrogen adsorption technique cannot be used, is demonstrated using the kinetics of methanol oxidation.