A fast, practical maximum loading point (MLP) calculation method is proposed in this study. The calculation process is based both on the geometrical properties of the load parameter space feasibility boundary and a load flow method with step size optimisation. Moreover, a practical procedure is added to the overall calculation process to include the operator's information on the acceptable error in the final result. The basic process is characterised by obtaining consecutive approximations of the MLP within the infeasible region. In each step, a correction factor based on the maximum acceptable error in the final MLP is applied. Reactive power generation limits are taken into account. The MLP is accurately obtained after just a few iterations, demonstrating that the proposed method is very efficient. Simulation results for IEEE test and realistic systems are shown to validate the proposed method. © 2011 The Institution of Engineering and Technology.