This paper compares different methods (Kragten, Guide to the expression of uncertainty in measurement -GUM-and Relative Uncertainty) to evaluate the measurement uncertainty in bimetallic thermometers. The motivation for the development of the work is based on a need detected in the industry to increase the metrological reliability of thermometers for temperature control in the most diverse measurement processes. The applied methodology is based on the concepts enshrined in the classical literature about the GUM, Kragten and Relative methods. The consolidated results confirmed that, for temperature measurement applications, the GUM method is more appropriate for estimating the measurement uncertainty. The value obtained was equal to 1.22 o C throughout the calibration range of the instrument. In conclusion, this work showed that an increase in metrological reliability for the measurement of temperature, fundamental magnitude in industrial processes, can be obtained by evaluating different methods for estimating the measurement uncertainty.