This research to represent a linear integer mathematical model applied to evaluate temperature uniformity. In general, when considering the temperature test chamber as a constant temperature chamber that has achieved an arbitrary uniform temperature, the uncertainty at that achieved temperature can be separated into the two factors of chronological temperature fluctuation in time, and spatial temperature fluctuation, referred to as temperature uniformity. The numerical illustrations and results substantiate that the model proposed is useful to simultaneously consider x and y axis when determining temperature uniformity. Moreover, we found that the linear model made a significant impact on uniformity of the chamber. It was, however, suggested the laboratory and customer have to agree the scope of the calibration requested, duration of the test, (previous stabilization and recording time), parameters to be determined (calibration of the set point, study of spatial distribution of temperature/humidity, study of temporal stability, etc.) loading conditions, etc. These calibration conditions have to be recorded by the laboratory