A modeling method for piezoresitive nanocantilevers using their geometrical parameters is described. The spring constant and the effective mass of piezoresistive nanocantilevers are formulated using theoretical and approximation equations, which shows a good agreement with the results of finite element analysis. The displacement sensitivity and minmum detectable force of piezoresistive nanocantilevers with non-uniform doping profiles are calculated by introducing a piezoresistive efficiency factor.