AbstractThe very wide varieties of geometries of irregular particles makes it difficult to study their motion also propose a simple and general equation to estimate their drag coefficient (CD). The goal of this research is to (1) experimentally validate the general CD correlation previously proposed by the authors of this article as a simple tool to estimate the CD of spherical to highly irregular particles over a wide ranges of Re from 0.001 to 300,000, and (2) examine and expand the reference model particles proposed by the authors to represent a wide range of irregular shapes (60 non‐flat and 36 flat). A comparison between the CD experimentally measured using reference model particles over a range of Re from 9 to 2481 and the CD estimated using general CD correlation, also comparing with CD correlations by others, demonstrated the accuracy and simplicity of the proposed general CD correlation.