This document proposes a method for evaluating the precision of T2* mapping techniques in MRI by estimating the standard deviation (SD) of each T2* measurement. The authors validate their SD estimation method using phantom experiments and show good correlation between estimated and measured SD values. They demonstrate potential clinical applications, such as masking unreliable pixels from motion or low signal-to-noise, to improve diagnosis. The SD maps provide a way to assess measurement noise and precision of different T2* mapping protocols.