Aim: Ureteral double J stent placement is a common urological procedure. There are many conditions that lead to a stent placement and some of them, mainly in pregnant female patients, have the contraindications of using X-ray. This study has the aim of proposing a mathematical model able to predict ureteral length finding a correlation between different physical data. Materials and methods: Between June 2007 and July 2009, 100 female patients who underwent ureteral stent placement were enrolled in this study. Patients with septic conditions, history or evidence of TCC, congenital and acquired kidney or ureteral malformations, and previous ureteral surgery were not enrolled.