Abstract
The propagation of uncertainties, when the International Temperature Scale of 1990 (ITS-90) is used by a standard platinum resistance thermometer (SPRT) calibrated at defining fixed points (DFP), can be solved by applying several approaches. The article presents an analysis of contribution of covariance between resistances of SPRT at the defining fixed points (DFP). Its effect on temperature measured by calibrated SPRT is demonstrated by using real calibration data.