Ultraviolet radiation is an important and highly energetic component of solar spectrum that needs to be monitored because is harmful to life on Earth, especially in areas where ozone layer has been depleted like Chile. The erythemal ultraviolet (UVER) radiation, corresponding to 280-315 nm, is the component of ultraviolet band most used to identify overexposure limits. In this work, four years of UVER measurements at the surface, carried out from January 1st, 2015 to December 31th, 2018, in Santiago City, Chile, are analyzed and used to develop a mathematical regression models to estimate UVER in terms of solar global irradiance (IG). The UVER models, obtained by fitting a second-degree polynomial, perform better during summer (RMSE=0.028, NRMSE=20%) and the worst in the winter (RMSE=0.015, NRMSE=54%) for hourly values. Similarly, performance is presented by daily values of UVER.