This paper describes mesh sizing functions for discretization of a wind turbine blade as a shell structure. Two different functions, one along the blade span and the other chord-wise, are presented. The effect of the magnitude of the aerodynamic force has been considered in a span-wise mesh sizing function to obtain a force-adaptive mesh generator, applicable when the blade needs to be analysed as a part of an aero-structure problem. The direction of the aerodynamic force has been considered in the chord-wise mesh sizing function to improve the mesh efficiency. Results show a large improvement in the rate of convergence when the direction of the external force contributes towards the chord-wise mesh size.