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The classification of coal resources used in Indonesia is currently based on the guidelines of SNI 5015:2019 which is considering three differences in geological and data complexities, i.e. simple, moderate, and complex. This study performed the Drill Hole Spacing Analysis (DHSA) using Global Estimation Variance (GEV) method to optimize and evaluate the coal resources of a seam in a coal mine site. This study was conducted for coal deposits in the Muara Enim Formation, South Sumatra Basin, Indonesia. The results of this study showed that Pit X with simple geological complexity has optimum drill hole spacing of 350 m, 1000 m, and >1000 m, respectively for the measured, indicated, and inferred categories. This study showed that the optimum drill hole spacing determined by the GEV in general was more confident (closer) compared to the drill hole spacing required in SNI 5015:2019.