Abstract: The study is devoted to the estimation of absolute errors concerning the methods of Correlated Color Temperature (CCT) calculation using the program developed by the researcher. The graphs of absolute error distribution in the area of CCT determination are presented. According to the obtained results, recommendations are offered on the use of abovementioned methods in the practice of colorimetric measurements. The study also compares the "classical" version of Robertson method which uses 31 isotherms, and the variants with a large number of isotherms. It is shown that an error decreases with a step decrease between isotherms. The calculation program is implemented using Python language and Numpy library, the tables are calculated also using Python language and Scipy library, the graphs are built using Matplotlib library.