A method for characterising the surface profile of a component comprises the steps of a) dividing the surface into at least two regions; b) for each region, measuring the surface and selecting a number of measured points to define a co-ordinate dataset for the region; c) for each region, applying a curve-fitting algorithm to the dataset for the region to define the surface profile of the region; d) combining the defined surface profiles for the regions to produce a defined surface profile for the aerofoil surface. The characterisation may be used in the design, analysis and manufacturing steps of product development, thereby decreasing the total time and work required.