In the present paper, ellipse-like approximations are considered with the aim of minimizing the difference between the results of direct and software measurements. The human body can only be approximately represented by elliptic cross sections, and these can vary for each individual. We show that better results are obtained by adapting the fit to the body shape based on a simple criterion. Based on this study, we have selected two mathematical models to estimate upper human body circumferences.The result is a fully trained system that can choose the best ellipse equation according to the human body shape to calculate human body circumferences.