Uniform mixing is crucial for different types of molecules, powders, and materials in several chemical, mineral, cement, and drug companies. However, there is no effective index to evaluate the uniformity of mixing of multiple components. This study proposes a non-sampling mixing index (SMI) that is applicable to both multiple mixtures with more than two components as well as binary mixtures. The proposed mixing index estimates a mixing state by using all subdomain mixing information for all particles without requiring sampling. In the study, the index was used to predict the mixing of different types of metallic particles in a screw blender. A discrete element based numerical technique was used to determine the transient location of particles in a screw blender at different rotation rates. The effectiveness of the SMI was demonstrated by comparing it with other representative mixing indices. The effectiveness was elucidated using a model of a binary system in which two groups of particles were mixed from 0% (no mixing) to 100% (perfect mixing). The SMI indicated a linear correlation from 0 to near 1 between test mixing conditions and the mixing indices in contrast to other conventional methods that over-predicted the mixing conditions. With respect to the DEM simulation, the SMI displayed values between SMI = 0 at the initial stage and SMI = 0.9-0.94 at a fully random mixed condition for the rpm ranges corresponding to 15, 30, 45 and 60. The results also indicated that the SMI value of zero occurred at the boundaries with the exception of the bottom and that a considerably lower mixing index was obtained at boundaries as opposed to inner subdomains with respect to the fully random mixed condition (t = 20 s and rpm = 30). (C) 2017 Elsevier B.V. All rights reserved.