Crystallinity index (CrI) obtained from X-ray diffraction (XRD) technique is often utilized as a characterization parameter of lignocellulosic biomass. There exist a few methodologies to calculate CrI but the respective merit as lignocellulose characterization parameter is not very clear. Here four commonly employed CrI computational methods were applied to raw and torrefied biomasses (palm kernel shell and sugarcane bagasse), cellulose- and lignin-added raw biomasses and artificial mixtures of cellulose, hemicellulose and lignin in order to compare the effect of the composition of lignocellulosic biomass toward CrI calculated from Xray diffractogram. Calculated CrI systematically showed larger value than the weight percentage of cellulose contained in the samples. Among the four computational methods compared, Segal (single peak height ratio) method and Ruland-Vonk (two-peak area ratio) method appeared to give reasonable CrI numbers although they are still overestimating the cellulose weight ratio. The Ruland-Vonk method consistently gave the lowest CrI values among the methods examined. © 2023, Association of American Publishers. All rights reserved.