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In livestock science and meat science, muscle fiber characteristics have been evaluated based on a cross-sectional area (CSA) of muscle fiber. However, muscle fiber is not planar but cylindrical. Thus, muscle fiber volume and volume-based characteristics were evaluated in this study. In addition, their relationships to pork loin quality was assessed and compared with that of CSA-based muscle fiber characteristics. Muscle fiber type IIB was underestimated by CSA-based evaluations with 1.6 times in fiber size and 2.6 times in relative composition. The pennation angle, which ranged from 48.00° to 83.33°, determined the real CSA and total number of fibers (TNF) on the surface of a loin chop. Significant (P < 0.05) correlation coefficients were found: fiber volume (r = –0.37) and volume % (r = –0.37) of type IIX with loin length; volume % of type IIX with CIE L* (r = 0.40); volume % of types IIX (r = 0.39) and IIB (r = –0.39) with Warner-Bratzler shear force. Although those correlations to loin quality differed from those of CSA-based characteristics, the Z-scores did not show any significance between the 2 correlation coefficients, except for TNF. Therefore, the conventional methodology for muscle fiber characteristics can be used for evaluating the relationship to pork quality; however, the new methodology is more useful in estimating the characteristics of muscle fiber, which is elongated and cylindrical and to correct the underestimated fiber size and composition of type IIB.