Abstract: This paper presents the influence of reversibility on uncertainty of force measurements. In actual measurement, the coverage factor k of reversibility cannot be determined because of its unknown distribution, despite of the value of 1.732 defined in ISO376. The reversibility properties of force sensors are studied based on the definition of coverage factor. Using both discrete and continuous analyses, the actual distribution of reversibility are discussed and finally the coverage factor k is determined. The discrete random variable is transformed into a continuous one by estimating the kernel density. Then the probability density of the unknown distribution is simulated using the center method and the shortest coverage interval. The finally determined coverage factors corresponding to confidence intervals of 95% and 99% are 1.8463 and 2.2216, respectively.